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linux/fs/devfs/base.c
Jes Sorensen 1b1dcc1b57 [PATCH] mutex subsystem, semaphore to mutex: VFS, ->i_sem 
This patch converts the inode semaphore to a mutex. I have tested it on
XFS and compiled as much as one can consider on an ia64. Anyway your
luck with it might be different.

Modified-by: Ingo Molnar <mingo@elte.hu>

(finished the conversion)

Signed-off-by: Jes Sorensen <jes@sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2006-01-09 15:59:24 -08:00

2837 lines
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/* devfs (Device FileSystem) driver.
Copyright (C) 1998-2002 Richard Gooch
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public
License as published by the Free Software Foundation; either
version 2 of the License, or (at your option) any later version.
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with this library; if not, write to the Free
Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
Richard Gooch may be reached by email at rgooch@atnf.csiro.au
The postal address is:
Richard Gooch, c/o ATNF, P. O. Box 76, Epping, N.S.W., 2121, Australia.
ChangeLog
19980110 Richard Gooch <rgooch@atnf.csiro.au>
Original version.
v0.1
19980111 Richard Gooch <rgooch@atnf.csiro.au>
Created per-fs inode table rather than using inode->u.generic_ip
v0.2
19980111 Richard Gooch <rgooch@atnf.csiro.au>
Created .epoch inode which has a ctime of 0.
Fixed loss of named pipes when dentries lost.
Fixed loss of inode data when devfs_register() follows mknod().
v0.3
19980111 Richard Gooch <rgooch@atnf.csiro.au>
Fix for when compiling with CONFIG_KERNELD.
19980112 Richard Gooch <rgooch@atnf.csiro.au>
Fix for readdir() which sometimes didn't show entries.
Added <<tolerant>> option to <devfs_register>.
v0.4
19980113 Richard Gooch <rgooch@atnf.csiro.au>
Created <devfs_fill_file> function.
v0.5
19980115 Richard Gooch <rgooch@atnf.csiro.au>
Added subdirectory support. Major restructuring.
19980116 Richard Gooch <rgooch@atnf.csiro.au>
Fixed <find_by_dev> to not search major=0,minor=0.
Added symlink support.
v0.6
19980120 Richard Gooch <rgooch@atnf.csiro.au>
Created <devfs_mk_dir> function and support directory unregister
19980120 Richard Gooch <rgooch@atnf.csiro.au>
Auto-ownership uses real uid/gid rather than effective uid/gid.
v0.7
19980121 Richard Gooch <rgooch@atnf.csiro.au>
Supported creation of sockets.
v0.8
19980122 Richard Gooch <rgooch@atnf.csiro.au>
Added DEVFS_FL_HIDE_UNREG flag.
Interface change to <devfs_mk_symlink>.
Created <devfs_symlink> to support symlink(2).
v0.9
19980123 Richard Gooch <rgooch@atnf.csiro.au>
Added check to <devfs_fill_file> to check inode is in devfs.
Added optional traversal of symlinks.
v0.10
19980124 Richard Gooch <rgooch@atnf.csiro.au>
Created <devfs_get_flags> and <devfs_set_flags>.
v0.11
19980125 C. Scott Ananian <cananian@alumni.princeton.edu>
Created <devfs_find_handle>.
19980125 Richard Gooch <rgooch@atnf.csiro.au>
Allow removal of symlinks.
v0.12
19980125 Richard Gooch <rgooch@atnf.csiro.au>
Created <devfs_set_symlink_destination>.
19980126 Richard Gooch <rgooch@atnf.csiro.au>
Moved DEVFS_SUPER_MAGIC into header file.
Added DEVFS_FL_HIDE flag.
Created <devfs_get_maj_min>.
Created <devfs_get_handle_from_inode>.
Fixed minor bug in <find_by_dev>.
19980127 Richard Gooch <rgooch@atnf.csiro.au>
Changed interface to <find_by_dev>, <find_entry>,
<devfs_unregister>, <devfs_fill_file> and <devfs_find_handle>.
Fixed inode times when symlink created with symlink(2).
v0.13
19980129 C. Scott Ananian <cananian@alumni.princeton.edu>
Exported <devfs_set_symlink_destination>, <devfs_get_maj_min>
and <devfs_get_handle_from_inode>.
19980129 Richard Gooch <rgooch@atnf.csiro.au>
Created <devfs_unlink> to support unlink(2).
v0.14
19980129 Richard Gooch <rgooch@atnf.csiro.au>
Fixed kerneld support for entries in devfs subdirectories.
19980130 Richard Gooch <rgooch@atnf.csiro.au>
Bugfixes in <call_kerneld>.
v0.15
19980207 Richard Gooch <rgooch@atnf.csiro.au>
Call kerneld when looking up unregistered entries.
v0.16
19980326 Richard Gooch <rgooch@atnf.csiro.au>
Modified interface to <devfs_find_handle> for symlink traversal.
v0.17
19980331 Richard Gooch <rgooch@atnf.csiro.au>
Fixed persistence bug with device numbers for manually created
device files.
Fixed problem with recreating symlinks with different content.
v0.18
19980401 Richard Gooch <rgooch@atnf.csiro.au>
Changed to CONFIG_KMOD.
Hide entries which are manually unlinked.
Always invalidate devfs dentry cache when registering entries.
Created <devfs_rmdir> to support rmdir(2).
Ensure directories created by <devfs_mk_dir> are visible.
v0.19
19980402 Richard Gooch <rgooch@atnf.csiro.au>
Invalidate devfs dentry cache when making directories.
Invalidate devfs dentry cache when removing entries.
Fixed persistence bug with fifos.
v0.20
19980421 Richard Gooch <rgooch@atnf.csiro.au>
Print process command when debugging kerneld/kmod.
Added debugging for register/unregister/change operations.
19980422 Richard Gooch <rgooch@atnf.csiro.au>
Added "devfs=" boot options.
v0.21
19980426 Richard Gooch <rgooch@atnf.csiro.au>
No longer lock/unlock superblock in <devfs_put_super>.
Drop negative dentries when they are released.
Manage dcache more efficiently.
v0.22
19980427 Richard Gooch <rgooch@atnf.csiro.au>
Added DEVFS_FL_AUTO_DEVNUM flag.
v0.23
19980430 Richard Gooch <rgooch@atnf.csiro.au>
No longer set unnecessary methods.
v0.24
19980504 Richard Gooch <rgooch@atnf.csiro.au>
Added PID display to <call_kerneld> debugging message.
Added "after" debugging message to <call_kerneld>.
19980519 Richard Gooch <rgooch@atnf.csiro.au>
Added "diread" and "diwrite" boot options.
19980520 Richard Gooch <rgooch@atnf.csiro.au>
Fixed persistence problem with permissions.
v0.25
19980602 Richard Gooch <rgooch@atnf.csiro.au>
Support legacy device nodes.
Fixed bug where recreated inodes were hidden.
v0.26
19980602 Richard Gooch <rgooch@atnf.csiro.au>
Improved debugging in <get_vfs_inode>.
19980607 Richard Gooch <rgooch@atnf.csiro.au>
No longer free old dentries in <devfs_mk_dir>.
Free all dentries for a given entry when deleting inodes.
v0.27
19980627 Richard Gooch <rgooch@atnf.csiro.au>
Limit auto-device numbering to majors 128 to 239.
v0.28
19980629 Richard Gooch <rgooch@atnf.csiro.au>
Fixed inode times persistence problem.
v0.29
19980704 Richard Gooch <rgooch@atnf.csiro.au>
Fixed spelling in <devfs_readlink> debug.
Fixed bug in <devfs_setup> parsing "dilookup".
v0.30
19980705 Richard Gooch <rgooch@atnf.csiro.au>
Fixed devfs inode leak when manually recreating inodes.
Fixed permission persistence problem when recreating inodes.
v0.31
19980727 Richard Gooch <rgooch@atnf.csiro.au>
Removed harmless "unused variable" compiler warning.
Fixed modes for manually recreated device nodes.
v0.32
19980728 Richard Gooch <rgooch@atnf.csiro.au>
Added NULL devfs inode warning in <devfs_read_inode>.
Force all inode nlink values to 1.
v0.33
19980730 Richard Gooch <rgooch@atnf.csiro.au>
Added "dimknod" boot option.
Set inode nlink to 0 when freeing dentries.
Fixed modes for manually recreated symlinks.
v0.34
19980802 Richard Gooch <rgooch@atnf.csiro.au>
Fixed bugs in recreated directories and symlinks.
v0.35
19980806 Richard Gooch <rgooch@atnf.csiro.au>
Fixed bugs in recreated device nodes.
19980807 Richard Gooch <rgooch@atnf.csiro.au>
Fixed bug in currently unused <devfs_get_handle_from_inode>.
Defined new <devfs_handle_t> type.
Improved debugging when getting entries.
Fixed bug where directories could be emptied.
v0.36
19980809 Richard Gooch <rgooch@atnf.csiro.au>
Replaced dummy .epoch inode with .devfsd character device.
19980810 Richard Gooch <rgooch@atnf.csiro.au>
Implemented devfsd protocol revision 0.
v0.37
19980819 Richard Gooch <rgooch@atnf.csiro.au>
Added soothing message to warning in <devfs_d_iput>.
v0.38
19980829 Richard Gooch <rgooch@atnf.csiro.au>
Use GCC extensions for structure initialisations.
Implemented async open notification.
Incremented devfsd protocol revision to 1.
v0.39
19980908 Richard Gooch <rgooch@atnf.csiro.au>
Moved async open notification to end of <devfs_open>.
v0.40
19980910 Richard Gooch <rgooch@atnf.csiro.au>
Prepended "/dev/" to module load request.
Renamed <call_kerneld> to <call_kmod>.
v0.41
19980910 Richard Gooch <rgooch@atnf.csiro.au>
Fixed typo "AYSNC" -> "ASYNC".
v0.42
19980910 Richard Gooch <rgooch@atnf.csiro.au>
Added open flag for files.
v0.43
19980927 Richard Gooch <rgooch@atnf.csiro.au>
Set i_blocks=0 and i_blksize=1024 in <devfs_read_inode>.
v0.44
19981005 Richard Gooch <rgooch@atnf.csiro.au>
Added test for empty <<name>> in <devfs_find_handle>.
Renamed <generate_path> to <devfs_generate_path> and published.
v0.45
19981006 Richard Gooch <rgooch@atnf.csiro.au>
Created <devfs_get_fops>.
v0.46
19981007 Richard Gooch <rgooch@atnf.csiro.au>
Limit auto-device numbering to majors 144 to 239.
v0.47
19981010 Richard Gooch <rgooch@atnf.csiro.au>
Updated <devfs_follow_link> for VFS change in 2.1.125.
v0.48
19981022 Richard Gooch <rgooch@atnf.csiro.au>
Created DEVFS_ FL_COMPAT flag.
v0.49
19981023 Richard Gooch <rgooch@atnf.csiro.au>
Created "nocompat" boot option.
v0.50
19981025 Richard Gooch <rgooch@atnf.csiro.au>
Replaced "mount" boot option with "nomount".
v0.51
19981110 Richard Gooch <rgooch@atnf.csiro.au>
Created "only" boot option.
v0.52
19981112 Richard Gooch <rgooch@atnf.csiro.au>
Added DEVFS_FL_REMOVABLE flag.
v0.53
19981114 Richard Gooch <rgooch@atnf.csiro.au>
Only call <scan_dir_for_removable> on first call to
<devfs_readdir>.
v0.54
19981205 Richard Gooch <rgooch@atnf.csiro.au>
Updated <devfs_rmdir> for VFS change in 2.1.131.
v0.55
19981218 Richard Gooch <rgooch@atnf.csiro.au>
Created <devfs_mk_compat>.
19981220 Richard Gooch <rgooch@atnf.csiro.au>
Check for partitions on removable media in <devfs_lookup>.
v0.56
19990118 Richard Gooch <rgooch@atnf.csiro.au>
Added support for registering regular files.
Created <devfs_set_file_size>.
Update devfs inodes from entries if not changed through FS.
v0.57
19990124 Richard Gooch <rgooch@atnf.csiro.au>
Fixed <devfs_fill_file> to only initialise temporary inodes.
Trap for NULL fops in <devfs_register>.
Return -ENODEV in <devfs_fill_file> for non-driver inodes.
v0.58
19990126 Richard Gooch <rgooch@atnf.csiro.au>
Switched from PATH_MAX to DEVFS_PATHLEN.
v0.59
19990127 Richard Gooch <rgooch@atnf.csiro.au>
Created "nottycompat" boot option.
v0.60
19990318 Richard Gooch <rgooch@atnf.csiro.au>
Fixed <devfsd_read> to not overrun event buffer.
v0.61
19990329 Richard Gooch <rgooch@atnf.csiro.au>
Created <devfs_auto_unregister>.
v0.62
19990330 Richard Gooch <rgooch@atnf.csiro.au>
Don't return unregistred entries in <devfs_find_handle>.
Panic in <devfs_unregister> if entry unregistered.
19990401 Richard Gooch <rgooch@atnf.csiro.au>
Don't panic in <devfs_auto_unregister> for duplicates.
v0.63
19990402 Richard Gooch <rgooch@atnf.csiro.au>
Don't unregister already unregistered entries in <unregister>.
v0.64
19990510 Richard Gooch <rgooch@atnf.csiro.au>
Disable warning messages when unable to read partition table for
removable media.
v0.65
19990512 Richard Gooch <rgooch@atnf.csiro.au>
Updated <devfs_lookup> for VFS change in 2.3.1-pre1.
Created "oops-on-panic" boot option.
Improved debugging in <devfs_register> and <devfs_unregister>.
v0.66
19990519 Richard Gooch <rgooch@atnf.csiro.au>
Added documentation for some functions.
19990525 Richard Gooch <rgooch@atnf.csiro.au>
Removed "oops-on-panic" boot option: now always Oops.
v0.67
19990531 Richard Gooch <rgooch@atnf.csiro.au>
Improved debugging in <devfs_register>.
v0.68
19990604 Richard Gooch <rgooch@atnf.csiro.au>
Added "diunlink" and "nokmod" boot options.
Removed superfluous warning message in <devfs_d_iput>.
v0.69
19990611 Richard Gooch <rgooch@atnf.csiro.au>
Took account of change to <d_alloc_root>.
v0.70
19990614 Richard Gooch <rgooch@atnf.csiro.au>
Created separate event queue for each mounted devfs.
Removed <devfs_invalidate_dcache>.
Created new ioctl()s.
Incremented devfsd protocol revision to 3.
Fixed bug when re-creating directories: contents were lost.
Block access to inodes until devfsd updates permissions.
19990615 Richard Gooch <rgooch@atnf.csiro.au>
Support 2.2.x kernels.
v0.71
19990623 Richard Gooch <rgooch@atnf.csiro.au>
Switched to sending process uid/gid to devfsd.
Renamed <call_kmod> to <try_modload>.
Added DEVFSD_NOTIFY_LOOKUP event.
19990624 Richard Gooch <rgooch@atnf.csiro.au>
Added DEVFSD_NOTIFY_CHANGE event.
Incremented devfsd protocol revision to 4.
v0.72
19990713 Richard Gooch <rgooch@atnf.csiro.au>
Return EISDIR rather than EINVAL for read(2) on directories.
v0.73
19990809 Richard Gooch <rgooch@atnf.csiro.au>
Changed <devfs_setup> to new __init scheme.
v0.74
19990901 Richard Gooch <rgooch@atnf.csiro.au>
Changed remaining function declarations to new __init scheme.
v0.75
19991013 Richard Gooch <rgooch@atnf.csiro.au>
Created <devfs_get_info>, <devfs_set_info>,
<devfs_get_first_child> and <devfs_get_next_sibling>.
Added <<dir>> parameter to <devfs_register>, <devfs_mk_compat>,
<devfs_mk_dir> and <devfs_find_handle>.
Work sponsored by SGI.
v0.76
19991017 Richard Gooch <rgooch@atnf.csiro.au>
Allow multiple unregistrations.
Work sponsored by SGI.
v0.77
19991026 Richard Gooch <rgooch@atnf.csiro.au>
Added major and minor number to devfsd protocol.
Incremented devfsd protocol revision to 5.
Work sponsored by SGI.
v0.78
19991030 Richard Gooch <rgooch@atnf.csiro.au>
Support info pointer for all devfs entry types.
Added <<info>> parameter to <devfs_mk_dir> and
<devfs_mk_symlink>.
Work sponsored by SGI.
v0.79
19991031 Richard Gooch <rgooch@atnf.csiro.au>
Support "../" when searching devfs namespace.
Work sponsored by SGI.
v0.80
19991101 Richard Gooch <rgooch@atnf.csiro.au>
Created <devfs_get_unregister_slave>.
Work sponsored by SGI.
v0.81
19991103 Richard Gooch <rgooch@atnf.csiro.au>
Exported <devfs_get_parent>.
Work sponsored by SGI.
v0.82
19991104 Richard Gooch <rgooch@atnf.csiro.au>
Removed unused <devfs_set_symlink_destination>.
19991105 Richard Gooch <rgooch@atnf.csiro.au>
Do not hide entries from devfsd or children.
Removed DEVFS_ FL_TTY_COMPAT flag.
Removed "nottycompat" boot option.
Removed <devfs_mk_compat>.
Work sponsored by SGI.
v0.83
19991107 Richard Gooch <rgooch@atnf.csiro.au>
Added DEVFS_FL_WAIT flag.
Work sponsored by SGI.
v0.84
19991107 Richard Gooch <rgooch@atnf.csiro.au>
Support new "disc" naming scheme in <get_removable_partition>.
Allow NULL fops in <devfs_register>.
Work sponsored by SGI.
v0.85
19991110 Richard Gooch <rgooch@atnf.csiro.au>
Fall back to major table if NULL fops given to <devfs_register>.
Work sponsored by SGI.
v0.86
19991204 Richard Gooch <rgooch@atnf.csiro.au>
Support fifos when unregistering.
Work sponsored by SGI.
v0.87
19991209 Richard Gooch <rgooch@atnf.csiro.au>
Removed obsolete DEVFS_ FL_COMPAT and DEVFS_ FL_TOLERANT flags.
Work sponsored by SGI.
v0.88
19991214 Richard Gooch <rgooch@atnf.csiro.au>
Removed kmod support.
Work sponsored by SGI.
v0.89
19991216 Richard Gooch <rgooch@atnf.csiro.au>
Improved debugging in <get_vfs_inode>.
Ensure dentries created by devfsd will be cleaned up.
Work sponsored by SGI.
v0.90
19991223 Richard Gooch <rgooch@atnf.csiro.au>
Created <devfs_get_name>.
Work sponsored by SGI.
v0.91
20000203 Richard Gooch <rgooch@atnf.csiro.au>
Ported to kernel 2.3.42.
Removed <devfs_fill_file>.
Work sponsored by SGI.
v0.92
20000306 Richard Gooch <rgooch@atnf.csiro.au>
Added DEVFS_ FL_NO_PERSISTENCE flag.
Removed unnecessary call to <update_devfs_inode_from_entry> in
<devfs_readdir>.
Work sponsored by SGI.
v0.93
20000413 Richard Gooch <rgooch@atnf.csiro.au>
Set inode->i_size to correct size for symlinks.
20000414 Richard Gooch <rgooch@atnf.csiro.au>
Only give lookup() method to directories to comply with new VFS
assumptions.
Work sponsored by SGI.
20000415 Richard Gooch <rgooch@atnf.csiro.au>
Remove unnecessary tests in symlink methods.
Don't kill existing block ops in <devfs_read_inode>.
Work sponsored by SGI.
v0.94
20000424 Richard Gooch <rgooch@atnf.csiro.au>
Don't create missing directories in <devfs_find_handle>.
Work sponsored by SGI.
v0.95
20000430 Richard Gooch <rgooch@atnf.csiro.au>
Added CONFIG_DEVFS_MOUNT.
Work sponsored by SGI.
v0.96
20000608 Richard Gooch <rgooch@atnf.csiro.au>
Disabled multi-mount capability (use VFS bindings instead).
Work sponsored by SGI.
v0.97
20000610 Richard Gooch <rgooch@atnf.csiro.au>
Switched to FS_SINGLE to disable multi-mounts.
20000612 Richard Gooch <rgooch@atnf.csiro.au>
Removed module support.
Removed multi-mount code.
Removed compatibility macros: VFS has changed too much.
Work sponsored by SGI.
v0.98
20000614 Richard Gooch <rgooch@atnf.csiro.au>
Merged devfs inode into devfs entry.
Work sponsored by SGI.
v0.99
20000619 Richard Gooch <rgooch@atnf.csiro.au>
Removed dead code in <devfs_register> which used to call
<free_dentries>.
Work sponsored by SGI.
v0.100
20000621 Richard Gooch <rgooch@atnf.csiro.au>
Changed interface to <devfs_register>.
Work sponsored by SGI.
v0.101
20000622 Richard Gooch <rgooch@atnf.csiro.au>
Simplified interface to <devfs_mk_symlink> and <devfs_mk_dir>.
Simplified interface to <devfs_find_handle>.
Work sponsored by SGI.
v0.102
20010519 Richard Gooch <rgooch@atnf.csiro.au>
Ensure <devfs_generate_path> terminates string for root entry.
Exported <devfs_get_name> to modules.
20010520 Richard Gooch <rgooch@atnf.csiro.au>
Make <devfs_mk_symlink> send events to devfsd.
Cleaned up option processing in <devfs_setup>.
20010521 Richard Gooch <rgooch@atnf.csiro.au>
Fixed bugs in handling symlinks: could leak or cause Oops.
20010522 Richard Gooch <rgooch@atnf.csiro.au>
Cleaned up directory handling by separating fops.
v0.103
20010601 Richard Gooch <rgooch@atnf.csiro.au>
Fixed handling of inverted options in <devfs_setup>.
v0.104
20010604 Richard Gooch <rgooch@atnf.csiro.au>
Adjusted <try_modload> to account for <devfs_generate_path> fix.
v0.105
20010617 Richard Gooch <rgooch@atnf.csiro.au>
Answered question posed by Al Viro and removed his comments.
Moved setting of registered flag after other fields are changed.
Fixed race between <devfsd_close> and <devfsd_notify_one>.
Global VFS changes added bogus BKL to <devfsd_close>: removed.
Widened locking in <devfs_readlink> and <devfs_follow_link>.
Replaced <devfsd_read> stack usage with <devfsd_ioctl> kmalloc.
Simplified locking in <devfsd_ioctl> and fixed memory leak.
v0.106
20010709 Richard Gooch <rgooch@atnf.csiro.au>
Removed broken devnum allocation and use <devfs_alloc_devnum>.
Fixed old devnum leak by calling new <devfs_dealloc_devnum>.
v0.107
20010712 Richard Gooch <rgooch@atnf.csiro.au>
Fixed bug in <devfs_setup> which could hang boot process.
v0.108
20010730 Richard Gooch <rgooch@atnf.csiro.au>
Added DEVFSD_NOTIFY_DELETE event.
20010801 Richard Gooch <rgooch@atnf.csiro.au>
Removed #include <asm/segment.h>.
v0.109
20010807 Richard Gooch <rgooch@atnf.csiro.au>
Fixed inode table races by removing it and using
inode->u.generic_ip instead.
Moved <devfs_read_inode> into <get_vfs_inode>.
Moved <devfs_write_inode> into <devfs_notify_change>.
v0.110
20010808 Richard Gooch <rgooch@atnf.csiro.au>
Fixed race in <devfs_do_symlink> for uni-processor.
v0.111
20010818 Richard Gooch <rgooch@atnf.csiro.au>
Removed remnant of multi-mount support in <devfs_mknod>.
Removed unused DEVFS_FL_SHOW_UNREG flag.
v0.112
20010820 Richard Gooch <rgooch@atnf.csiro.au>
Removed nlink field from struct devfs_inode.
v0.113
20010823 Richard Gooch <rgooch@atnf.csiro.au>
Replaced BKL with global rwsem to protect symlink data (quick
and dirty hack).
v0.114
20010827 Richard Gooch <rgooch@atnf.csiro.au>
Replaced global rwsem for symlink with per-link refcount.
v0.115
20010919 Richard Gooch <rgooch@atnf.csiro.au>
Set inode->i_mapping->a_ops for block nodes in <get_vfs_inode>.
v0.116
20011008 Richard Gooch <rgooch@atnf.csiro.au>
Fixed overrun in <devfs_link> by removing function (not needed).
20011009 Richard Gooch <rgooch@atnf.csiro.au>
Fixed buffer underrun in <try_modload>.
20011029 Richard Gooch <rgooch@atnf.csiro.au>
Fixed race in <devfsd_ioctl> when setting event mask.
20011114 Richard Gooch <rgooch@atnf.csiro.au>
First release of new locking code.
v1.0
20011117 Richard Gooch <rgooch@atnf.csiro.au>
Discard temporary buffer, now use "%s" for dentry names.
20011118 Richard Gooch <rgooch@atnf.csiro.au>
Don't generate path in <try_modload>: use fake entry instead.
Use "existing" directory in <_devfs_make_parent_for_leaf>.
20011122 Richard Gooch <rgooch@atnf.csiro.au>
Use slab cache rather than fixed buffer for devfsd events.
v1.1
20011125 Richard Gooch <rgooch@atnf.csiro.au>
Send DEVFSD_NOTIFY_REGISTERED events in <devfs_mk_dir>.
20011127 Richard Gooch <rgooch@atnf.csiro.au>
Fixed locking bug in <devfs_d_revalidate_wait> due to typo.
Do not send CREATE, CHANGE, ASYNC_OPEN or DELETE events from
devfsd or children.
v1.2
20011202 Richard Gooch <rgooch@atnf.csiro.au>
Fixed bug in <devfsd_read>: was dereferencing freed pointer.
v1.3
20011203 Richard Gooch <rgooch@atnf.csiro.au>
Fixed bug in <devfsd_close>: was dereferencing freed pointer.
Added process group check for devfsd privileges.
v1.4
20011204 Richard Gooch <rgooch@atnf.csiro.au>
Use SLAB_ATOMIC in <devfsd_notify_de> from <devfs_d_delete>.
v1.5
20011211 Richard Gooch <rgooch@atnf.csiro.au>
Return old entry in <devfs_mk_dir> for 2.4.x kernels.
20011212 Richard Gooch <rgooch@atnf.csiro.au>
Increment refcount on module in <check_disc_changed>.
20011215 Richard Gooch <rgooch@atnf.csiro.au>
Created <devfs_get_handle> and exported <devfs_put>.
Increment refcount on module in <devfs_get_ops>.
Created <devfs_put_ops>.
v1.6
20011216 Richard Gooch <rgooch@atnf.csiro.au>
Added poisoning to <devfs_put>.
Improved debugging messages.
v1.7
20011221 Richard Gooch <rgooch@atnf.csiro.au>
Corrected (made useful) debugging message in <unregister>.
Moved <kmem_cache_create> in <mount_devfs_fs> to <init_devfs_fs>
20011224 Richard Gooch <rgooch@atnf.csiro.au>
Added magic number to guard against scribbling drivers.
20011226 Richard Gooch <rgooch@atnf.csiro.au>
Only return old entry in <devfs_mk_dir> if a directory.
Defined macros for error and debug messages.
v1.8
20020113 Richard Gooch <rgooch@atnf.csiro.au>
Fixed (rare, old) race in <devfs_lookup>.
v1.9
20020120 Richard Gooch <rgooch@atnf.csiro.au>
Fixed deadlock bug in <devfs_d_revalidate_wait>.
Tag VFS deletable in <devfs_mk_symlink> if handle ignored.
v1.10
20020129 Richard Gooch <rgooch@atnf.csiro.au>
Added KERN_* to remaining messages.
Cleaned up declaration of <stat_read>.
v1.11
20020219 Richard Gooch <rgooch@atnf.csiro.au>
Changed <devfs_rmdir> to allow later additions if not yet empty.
v1.12
20020406 Richard Gooch <rgooch@atnf.csiro.au>
Removed silently introduced calls to lock_kernel() and
unlock_kernel() due to recent VFS locking changes. BKL isn't
required in devfs.
v1.13
20020428 Richard Gooch <rgooch@atnf.csiro.au>
Removed 2.4.x compatibility code.
v1.14
20020510 Richard Gooch <rgooch@atnf.csiro.au>
Added BKL to <devfs_open> because drivers still need it.
v1.15
20020512 Richard Gooch <rgooch@atnf.csiro.au>
Protected <scan_dir_for_removable> and <get_removable_partition>
from changing directory contents.
v1.16
20020514 Richard Gooch <rgooch@atnf.csiro.au>
Minor cleanup of <scan_dir_for_removable>.
v1.17
20020721 Richard Gooch <rgooch@atnf.csiro.au>
Switched to ISO C structure field initialisers.
Switch to set_current_state() and move before add_wait_queue().
20020722 Richard Gooch <rgooch@atnf.csiro.au>
Fixed devfs entry leak in <devfs_readdir> when *readdir fails.
v1.18
20020725 Richard Gooch <rgooch@atnf.csiro.au>
Created <devfs_find_and_unregister>.
v1.19
20020728 Richard Gooch <rgooch@atnf.csiro.au>
Removed deprecated <devfs_find_handle>.
v1.20
20020820 Richard Gooch <rgooch@atnf.csiro.au>
Fixed module unload race in <devfs_open>.
v1.21
20021013 Richard Gooch <rgooch@atnf.csiro.au>
Removed DEVFS_ FL_AUTO_OWNER.
Switched lingering structure field initialiser to ISO C.
Added locking when updating FCB flags.
v1.22
*/
#include <linux/types.h>
#include <linux/errno.h>
#include <linux/time.h>
#include <linux/tty.h>
#include <linux/timer.h>
#include <linux/config.h>
#include <linux/kernel.h>
#include <linux/wait.h>
#include <linux/string.h>
#include <linux/slab.h>
#include <linux/ioport.h>
#include <linux/delay.h>
#include <linux/ctype.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/devfs_fs.h>
#include <linux/devfs_fs_kernel.h>
#include <linux/smp_lock.h>
#include <linux/smp.h>
#include <linux/rwsem.h>
#include <linux/sched.h>
#include <linux/namei.h>
#include <linux/bitops.h>
#include <asm/uaccess.h>
#include <asm/io.h>
#include <asm/processor.h>
#include <asm/system.h>
#include <asm/pgtable.h>
#include <asm/atomic.h>
#define DEVFS_VERSION "2004-01-31"
#define DEVFS_NAME "devfs"
#define FIRST_INODE 1
#define STRING_LENGTH 256
#define FAKE_BLOCK_SIZE 1024
#define POISON_PTR ( *(void **) poison_array )
#define MAGIC_VALUE 0x327db823
#ifndef TRUE
# define TRUE 1
# define FALSE 0
#endif
#define MODE_DIR (S_IFDIR | S_IWUSR | S_IRUGO | S_IXUGO)
#define DEBUG_NONE 0x0000000
#define DEBUG_MODULE_LOAD 0x0000001
#define DEBUG_REGISTER 0x0000002
#define DEBUG_UNREGISTER 0x0000004
#define DEBUG_FREE 0x0000008
#define DEBUG_SET_FLAGS 0x0000010
#define DEBUG_S_READ 0x0000100 /* Break */
#define DEBUG_I_LOOKUP 0x0001000 /* Break */
#define DEBUG_I_CREATE 0x0002000
#define DEBUG_I_GET 0x0004000
#define DEBUG_I_CHANGE 0x0008000
#define DEBUG_I_UNLINK 0x0010000
#define DEBUG_I_RLINK 0x0020000
#define DEBUG_I_FLINK 0x0040000
#define DEBUG_I_MKNOD 0x0080000
#define DEBUG_F_READDIR 0x0100000 /* Break */
#define DEBUG_D_DELETE 0x1000000 /* Break */
#define DEBUG_D_RELEASE 0x2000000
#define DEBUG_D_IPUT 0x4000000
#define DEBUG_ALL 0xfffffff
#define DEBUG_DISABLED DEBUG_NONE
#define OPTION_NONE 0x00
#define OPTION_MOUNT 0x01
#define PRINTK(format, args...) \
{printk (KERN_ERR "%s" format, __FUNCTION__ , ## args);}
#define OOPS(format, args...) \
{printk (KERN_CRIT "%s" format, __FUNCTION__ , ## args); \
printk ("Forcing Oops\n"); \
BUG();}
#ifdef CONFIG_DEVFS_DEBUG
# define VERIFY_ENTRY(de) \
{if ((de) && (de)->magic_number != MAGIC_VALUE) \
OOPS ("(%p): bad magic value: %x\n", (de), (de)->magic_number);}
# define WRITE_ENTRY_MAGIC(de,magic) (de)->magic_number = (magic)
# define DPRINTK(flag, format, args...) \
{if (devfs_debug & flag) \
printk (KERN_INFO "%s" format, __FUNCTION__ , ## args);}
#else
# define VERIFY_ENTRY(de)
# define WRITE_ENTRY_MAGIC(de,magic)
# define DPRINTK(flag, format, args...)
#endif
typedef struct devfs_entry *devfs_handle_t;
struct directory_type {
rwlock_t lock; /* Lock for searching(R)/updating(W) */
struct devfs_entry *first;
struct devfs_entry *last;
unsigned char no_more_additions:1;
};
struct symlink_type {
unsigned int length; /* Not including the NULL-termimator */
char *linkname; /* This is NULL-terminated */
};
struct devfs_inode { /* This structure is for "persistent" inode storage */
struct dentry *dentry;
struct timespec atime;
struct timespec mtime;
struct timespec ctime;
unsigned int ino; /* Inode number as seen in the VFS */
uid_t uid;
gid_t gid;
};
struct devfs_entry {
#ifdef CONFIG_DEVFS_DEBUG
unsigned int magic_number;
#endif
void *info;
atomic_t refcount; /* When this drops to zero, it's unused */
union {
struct directory_type dir;
dev_t dev;
struct symlink_type symlink;
const char *name; /* Only used for (mode == 0) */
} u;
struct devfs_entry *prev; /* Previous entry in the parent directory */
struct devfs_entry *next; /* Next entry in the parent directory */
struct devfs_entry *parent; /* The parent directory */
struct devfs_inode inode;
umode_t mode;
unsigned short namelen; /* I think 64k+ filenames are a way off... */
unsigned char vfs:1; /* Whether the VFS may delete the entry */
char name[1]; /* This is just a dummy: the allocated array
is bigger. This is NULL-terminated */
};
/* The root of the device tree */
static struct devfs_entry *root_entry;
struct devfsd_buf_entry {
struct devfs_entry *de; /* The name is generated with this */
unsigned short type; /* The type of event */
umode_t mode;
uid_t uid;
gid_t gid;
struct devfsd_buf_entry *next;
};
struct fs_info { /* This structure is for the mounted devfs */
struct super_block *sb;
spinlock_t devfsd_buffer_lock; /* Lock when inserting/deleting events */
struct devfsd_buf_entry *devfsd_first_event;
struct devfsd_buf_entry *devfsd_last_event;
volatile int devfsd_sleeping;
volatile struct task_struct *devfsd_task;
volatile pid_t devfsd_pgrp;
volatile struct file *devfsd_file;
struct devfsd_notify_struct *devfsd_info;
volatile unsigned long devfsd_event_mask;
atomic_t devfsd_overrun_count;
wait_queue_head_t devfsd_wait_queue; /* Wake devfsd on input */
wait_queue_head_t revalidate_wait_queue; /* Wake when devfsd sleeps */
};
static struct fs_info fs_info = {.devfsd_buffer_lock = SPIN_LOCK_UNLOCKED };
static kmem_cache_t *devfsd_buf_cache;
#ifdef CONFIG_DEVFS_DEBUG
static unsigned int devfs_debug_init __initdata = DEBUG_NONE;
static unsigned int devfs_debug = DEBUG_NONE;
static DEFINE_SPINLOCK(stat_lock);
static unsigned int stat_num_entries;
static unsigned int stat_num_bytes;
#endif
static unsigned char poison_array[8] =
{ 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a };
#ifdef CONFIG_DEVFS_MOUNT
static unsigned int boot_options = OPTION_MOUNT;
#else
static unsigned int boot_options = OPTION_NONE;
#endif
/* Forward function declarations */
static devfs_handle_t _devfs_walk_path(struct devfs_entry *dir,
const char *name, int namelen,
int traverse_symlink);
static ssize_t devfsd_read(struct file *file, char __user *buf, size_t len,
loff_t * ppos);
static int devfsd_ioctl(struct inode *inode, struct file *file,
unsigned int cmd, unsigned long arg);
static int devfsd_close(struct inode *inode, struct file *file);
#ifdef CONFIG_DEVFS_DEBUG
static ssize_t stat_read(struct file *file, char __user *buf, size_t len,
loff_t * ppos);
static struct file_operations stat_fops = {
.open = nonseekable_open,
.read = stat_read,
};
#endif
/* Devfs daemon file operations */
static struct file_operations devfsd_fops = {
.open = nonseekable_open,
.read = devfsd_read,
.ioctl = devfsd_ioctl,
.release = devfsd_close,
};
/* Support functions follow */
/**
* devfs_get - Get a reference to a devfs entry.
* @de: The devfs entry.
*/
static struct devfs_entry *devfs_get(struct devfs_entry *de)
{
VERIFY_ENTRY(de);
if (de)
atomic_inc(&de->refcount);
return de;
} /* End Function devfs_get */
/**
* devfs_put - Put (release) a reference to a devfs entry.
* @de: The handle to the devfs entry.
*/
static void devfs_put(devfs_handle_t de)
{
if (!de)
return;
VERIFY_ENTRY(de);
if (de->info == POISON_PTR)
OOPS("(%p): poisoned pointer\n", de);
if (!atomic_dec_and_test(&de->refcount))
return;
if (de == root_entry)
OOPS("(%p): root entry being freed\n", de);
DPRINTK(DEBUG_FREE, "(%s): de: %p, parent: %p \"%s\"\n",
de->name, de, de->parent,
de->parent ? de->parent->name : "no parent");
if (S_ISLNK(de->mode))
kfree(de->u.symlink.linkname);
WRITE_ENTRY_MAGIC(de, 0);
#ifdef CONFIG_DEVFS_DEBUG
spin_lock(&stat_lock);
--stat_num_entries;
stat_num_bytes -= sizeof *de + de->namelen;
if (S_ISLNK(de->mode))
stat_num_bytes -= de->u.symlink.length + 1;
spin_unlock(&stat_lock);
#endif
de->info = POISON_PTR;
kfree(de);
} /* End Function devfs_put */
/**
* _devfs_search_dir - Search for a devfs entry in a directory.
* @dir: The directory to search.
* @name: The name of the entry to search for.
* @namelen: The number of characters in @name.
*
* Search for a devfs entry in a directory and returns a pointer to the entry
* on success, else %NULL. The directory must be locked already.
* An implicit devfs_get() is performed on the returned entry.
*/
static struct devfs_entry *_devfs_search_dir(struct devfs_entry *dir,
const char *name,
unsigned int namelen)
{
struct devfs_entry *curr;
if (!S_ISDIR(dir->mode)) {
PRINTK("(%s): not a directory\n", dir->name);
return NULL;
}
for (curr = dir->u.dir.first; curr != NULL; curr = curr->next) {
if (curr->namelen != namelen)
continue;
if (memcmp(curr->name, name, namelen) == 0)
break;
/* Not found: try the next one */
}
return devfs_get(curr);
} /* End Function _devfs_search_dir */
/**
* _devfs_alloc_entry - Allocate a devfs entry.
* @name: the name of the entry
* @namelen: the number of characters in @name
* @mode: the mode for the entry
*
* Allocate a devfs entry and returns a pointer to the entry on success, else
* %NULL.
*/
static struct devfs_entry *_devfs_alloc_entry(const char *name,
unsigned int namelen,
umode_t mode)
{
struct devfs_entry *new;
static unsigned long inode_counter = FIRST_INODE;
static DEFINE_SPINLOCK(counter_lock);
if (name && (namelen < 1))
namelen = strlen(name);
if ((new = kmalloc(sizeof *new + namelen, GFP_KERNEL)) == NULL)
return NULL;
memset(new, 0, sizeof *new + namelen); /* Will set '\0' on name */
new->mode = mode;
if (S_ISDIR(mode))
rwlock_init(&new->u.dir.lock);
atomic_set(&new->refcount, 1);
spin_lock(&counter_lock);
new->inode.ino = inode_counter++;
spin_unlock(&counter_lock);
if (name)
memcpy(new->name, name, namelen);
new->namelen = namelen;
WRITE_ENTRY_MAGIC(new, MAGIC_VALUE);
#ifdef CONFIG_DEVFS_DEBUG
spin_lock(&stat_lock);
++stat_num_entries;
stat_num_bytes += sizeof *new + namelen;
spin_unlock(&stat_lock);
#endif
return new;
} /* End Function _devfs_alloc_entry */
/**
* _devfs_append_entry - Append a devfs entry to a directory's child list.
* @dir: The directory to add to.
* @de: The devfs entry to append.
* @old_de: If an existing entry exists, it will be written here. This may
* be %NULL. An implicit devfs_get() is performed on this entry.
*
* Append a devfs entry to a directory's list of children, checking first to
* see if an entry of the same name exists. The directory will be locked.
* The value 0 is returned on success, else a negative error code.
* On failure, an implicit devfs_put() is performed on %de.
*/
static int _devfs_append_entry(devfs_handle_t dir, devfs_handle_t de,
devfs_handle_t * old_de)
{
int retval;
if (old_de)
*old_de = NULL;
if (!S_ISDIR(dir->mode)) {
PRINTK("(%s): dir: \"%s\" is not a directory\n", de->name,
dir->name);
devfs_put(de);
return -ENOTDIR;
}
write_lock(&dir->u.dir.lock);
if (dir->u.dir.no_more_additions)
retval = -ENOENT;
else {
struct devfs_entry *old;
old = _devfs_search_dir(dir, de->name, de->namelen);
if (old_de)
*old_de = old;
else
devfs_put(old);
if (old == NULL) {
de->parent = dir;
de->prev = dir->u.dir.last;
/* Append to the directory's list of children */
if (dir->u.dir.first == NULL)
dir->u.dir.first = de;
else
dir->u.dir.last->next = de;
dir->u.dir.last = de;
retval = 0;
} else
retval = -EEXIST;
}
write_unlock(&dir->u.dir.lock);
if (retval)
devfs_put(de);
return retval;
} /* End Function _devfs_append_entry */
/**
* _devfs_get_root_entry - Get the root devfs entry.
*
* Returns the root devfs entry on success, else %NULL.
*
* TODO it must be called asynchronously due to the fact
* that devfs is initialized relatively late. Proper way
* is to remove module_init from init_devfs_fs and manually
* call it early enough during system init
*/
static struct devfs_entry *_devfs_get_root_entry(void)
{
struct devfs_entry *new;
static DEFINE_SPINLOCK(root_lock);
if (root_entry)
return root_entry;
new = _devfs_alloc_entry(NULL, 0, MODE_DIR);
if (new == NULL)
return NULL;
spin_lock(&root_lock);
if (root_entry) {
spin_unlock(&root_lock);
devfs_put(new);
return root_entry;
}
root_entry = new;
spin_unlock(&root_lock);
return root_entry;
} /* End Function _devfs_get_root_entry */
/**
* _devfs_descend - Descend down a tree using the next component name.
* @dir: The directory to search.
* @name: The component name to search for.
* @namelen: The length of %name.
* @next_pos: The position of the next '/' or '\0' is written here.
*
* Descend into a directory, searching for a component. This function forms
* the core of a tree-walking algorithm. The directory will be locked.
* The devfs entry corresponding to the component is returned. If there is
* no matching entry, %NULL is returned.
* An implicit devfs_get() is performed on the returned entry.
*/
static struct devfs_entry *_devfs_descend(struct devfs_entry *dir,
const char *name, int namelen,
int *next_pos)
{
const char *stop, *ptr;
struct devfs_entry *entry;
if ((namelen >= 3) && (strncmp(name, "../", 3) == 0)) { /* Special-case going to parent directory */
*next_pos = 3;
return devfs_get(dir->parent);
}
stop = name + namelen;
/* Search for a possible '/' */
for (ptr = name; (ptr < stop) && (*ptr != '/'); ++ptr) ;
*next_pos = ptr - name;
read_lock(&dir->u.dir.lock);
entry = _devfs_search_dir(dir, name, *next_pos);
read_unlock(&dir->u.dir.lock);
return entry;
} /* End Function _devfs_descend */
static devfs_handle_t _devfs_make_parent_for_leaf(struct devfs_entry *dir,
const char *name,
int namelen, int *leaf_pos)
{
int next_pos = 0;
if (dir == NULL)
dir = _devfs_get_root_entry();
if (dir == NULL)
return NULL;
devfs_get(dir);
/* Search for possible trailing component and ignore it */
for (--namelen; (namelen > 0) && (name[namelen] != '/'); --namelen) ;
*leaf_pos = (name[namelen] == '/') ? (namelen + 1) : 0;
for (; namelen > 0; name += next_pos, namelen -= next_pos) {
struct devfs_entry *de, *old = NULL;
if ((de =
_devfs_descend(dir, name, namelen, &next_pos)) == NULL) {
de = _devfs_alloc_entry(name, next_pos, MODE_DIR);
devfs_get(de);
if (!de || _devfs_append_entry(dir, de, &old)) {
devfs_put(de);
if (!old || !S_ISDIR(old->mode)) {
devfs_put(old);
devfs_put(dir);
return NULL;
}
de = old; /* Use the existing directory */
}
}
if (de == dir->parent) {
devfs_put(dir);
devfs_put(de);
return NULL;
}
devfs_put(dir);
dir = de;
if (name[next_pos] == '/')
++next_pos;
}
return dir;
} /* End Function _devfs_make_parent_for_leaf */
static devfs_handle_t _devfs_prepare_leaf(devfs_handle_t * dir,
const char *name, umode_t mode)
{
int namelen, leaf_pos;
struct devfs_entry *de;
namelen = strlen(name);
if ((*dir = _devfs_make_parent_for_leaf(*dir, name, namelen,
&leaf_pos)) == NULL) {
PRINTK("(%s): could not create parent path\n", name);
return NULL;
}
if ((de = _devfs_alloc_entry(name + leaf_pos, namelen - leaf_pos, mode))
== NULL) {
PRINTK("(%s): could not allocate entry\n", name);
devfs_put(*dir);
return NULL;
}
return de;
} /* End Function _devfs_prepare_leaf */
static devfs_handle_t _devfs_walk_path(struct devfs_entry *dir,
const char *name, int namelen,
int traverse_symlink)
{
int next_pos = 0;
if (dir == NULL)
dir = _devfs_get_root_entry();
if (dir == NULL)
return NULL;
devfs_get(dir);
for (; namelen > 0; name += next_pos, namelen -= next_pos) {
struct devfs_entry *de, *link;
if (!S_ISDIR(dir->mode)) {
devfs_put(dir);
return NULL;
}
if ((de =
_devfs_descend(dir, name, namelen, &next_pos)) == NULL) {
devfs_put(dir);
return NULL;
}
if (S_ISLNK(de->mode) && traverse_symlink) { /* Need to follow the link: this is a stack chomper */
/* FIXME what if it puts outside of mounted tree? */
link = _devfs_walk_path(dir, de->u.symlink.linkname,
de->u.symlink.length, TRUE);
devfs_put(de);
if (!link) {
devfs_put(dir);
return NULL;
}
de = link;
}
devfs_put(dir);
dir = de;
if (name[next_pos] == '/')
++next_pos;
}
return dir;
} /* End Function _devfs_walk_path */
/**
* _devfs_find_entry - Find a devfs entry.
* @dir: The handle to the parent devfs directory entry. If this is %NULL the
* name is relative to the root of the devfs.
* @name: The name of the entry. This may be %NULL.
* @traverse_symlink: If %TRUE then symbolic links are traversed.
*
* Returns the devfs_entry pointer on success, else %NULL. An implicit
* devfs_get() is performed.
*/
static struct devfs_entry *_devfs_find_entry(devfs_handle_t dir,
const char *name,
int traverse_symlink)
{
unsigned int namelen = strlen(name);
if (name[0] == '/') {
/* Skip leading pathname component */
if (namelen < 2) {
PRINTK("(%s): too short\n", name);
return NULL;
}
for (++name, --namelen; (*name != '/') && (namelen > 0);
++name, --namelen) ;
if (namelen < 2) {
PRINTK("(%s): too short\n", name);
return NULL;
}
++name;
--namelen;
}
return _devfs_walk_path(dir, name, namelen, traverse_symlink);
} /* End Function _devfs_find_entry */
static struct devfs_entry *get_devfs_entry_from_vfs_inode(struct inode *inode)
{
if (inode == NULL)
return NULL;
VERIFY_ENTRY((struct devfs_entry *)inode->u.generic_ip);
return inode->u.generic_ip;
} /* End Function get_devfs_entry_from_vfs_inode */
/**
* free_dentry - Free the dentry for a device entry and invalidate inode.
* @de: The entry.
*
* This must only be called after the entry has been unhooked from its
* parent directory.
*/
static void free_dentry(struct devfs_entry *de)
{
struct dentry *dentry = de->inode.dentry;
if (!dentry)
return;
spin_lock(&dcache_lock);
dget_locked(dentry);
spin_unlock(&dcache_lock);
/* Forcefully remove the inode */
if (dentry->d_inode != NULL)
dentry->d_inode->i_nlink = 0;
d_drop(dentry);
dput(dentry);
} /* End Function free_dentry */
/**
* is_devfsd_or_child - Test if the current process is devfsd or one of its children.
* @fs_info: The filesystem information.
*
* Returns %TRUE if devfsd or child, else %FALSE.
*/
static int is_devfsd_or_child(struct fs_info *fs_info)
{
struct task_struct *p = current;
if (p == fs_info->devfsd_task)
return (TRUE);
if (process_group(p) == fs_info->devfsd_pgrp)
return (TRUE);
read_lock(&tasklist_lock);
for (; p != &init_task; p = p->real_parent) {
if (p == fs_info->devfsd_task) {
read_unlock(&tasklist_lock);
return (TRUE);
}
}
read_unlock(&tasklist_lock);
return (FALSE);
} /* End Function is_devfsd_or_child */
/**
* devfsd_queue_empty - Test if devfsd has work pending in its event queue.
* @fs_info: The filesystem information.
*
* Returns %TRUE if the queue is empty, else %FALSE.
*/
static inline int devfsd_queue_empty(struct fs_info *fs_info)
{
return (fs_info->devfsd_last_event) ? FALSE : TRUE;
} /* End Function devfsd_queue_empty */
/**
* wait_for_devfsd_finished - Wait for devfsd to finish processing its event queue.
* @fs_info: The filesystem information.
*
* Returns %TRUE if no more waiting will be required, else %FALSE.
*/
static int wait_for_devfsd_finished(struct fs_info *fs_info)
{
DECLARE_WAITQUEUE(wait, current);
if (fs_info->devfsd_task == NULL)
return (TRUE);
if (devfsd_queue_empty(fs_info) && fs_info->devfsd_sleeping)
return TRUE;
if (is_devfsd_or_child(fs_info))
return (FALSE);
set_current_state(TASK_UNINTERRUPTIBLE);
add_wait_queue(&fs_info->revalidate_wait_queue, &wait);
if (!devfsd_queue_empty(fs_info) || !fs_info->devfsd_sleeping)
if (fs_info->devfsd_task)
schedule();
remove_wait_queue(&fs_info->revalidate_wait_queue, &wait);
__set_current_state(TASK_RUNNING);
return (TRUE);
} /* End Function wait_for_devfsd_finished */
/**
* devfsd_notify_de - Notify the devfsd daemon of a change.
* @de: The devfs entry that has changed. This and all parent entries will
* have their reference counts incremented if the event was queued.
* @type: The type of change.
* @mode: The mode of the entry.
* @uid: The user ID.
* @gid: The group ID.
* @fs_info: The filesystem info.
*
* Returns %TRUE if an event was queued and devfsd woken up, else %FALSE.
*/
static int devfsd_notify_de(struct devfs_entry *de,
unsigned short type, umode_t mode,
uid_t uid, gid_t gid, struct fs_info *fs_info)
{
struct devfsd_buf_entry *entry;
struct devfs_entry *curr;
if (!(fs_info->devfsd_event_mask & (1 << type)))
return (FALSE);
if ((entry = kmem_cache_alloc(devfsd_buf_cache, SLAB_KERNEL)) == NULL) {
atomic_inc(&fs_info->devfsd_overrun_count);
return (FALSE);
}
for (curr = de; curr != NULL; curr = curr->parent)
devfs_get(curr);
entry->de = de;
entry->type = type;
entry->mode = mode;
entry->uid = uid;
entry->gid = gid;
entry->next = NULL;
spin_lock(&fs_info->devfsd_buffer_lock);
if (!fs_info->devfsd_first_event)
fs_info->devfsd_first_event = entry;
if (fs_info->devfsd_last_event)
fs_info->devfsd_last_event->next = entry;
fs_info->devfsd_last_event = entry;
spin_unlock(&fs_info->devfsd_buffer_lock);
wake_up_interruptible(&fs_info->devfsd_wait_queue);
return (TRUE);
} /* End Function devfsd_notify_de */
/**
* devfsd_notify - Notify the devfsd daemon of a change.
* @de: The devfs entry that has changed.
* @type: The type of change event.
* @wait: If TRUE, the function waits for the daemon to finish processing
* the event.
*/
static void devfsd_notify(struct devfs_entry *de, unsigned short type)
{
devfsd_notify_de(de, type, de->mode, current->euid,
current->egid, &fs_info);
}
static int devfs_mk_dev(dev_t dev, umode_t mode, const char *fmt, va_list args)
{
struct devfs_entry *dir = NULL, *de;
char buf[64];
int error, n;
n = vsnprintf(buf, sizeof(buf), fmt, args);
if (n >= sizeof(buf) || !buf[0]) {
printk(KERN_WARNING "%s: invalid format string %s\n",
__FUNCTION__, fmt);
return -EINVAL;
}
de = _devfs_prepare_leaf(&dir, buf, mode);
if (!de) {
printk(KERN_WARNING "%s: could not prepare leaf for %s\n",
__FUNCTION__, buf);
return -ENOMEM; /* could be more accurate... */
}
de->u.dev = dev;
error = _devfs_append_entry(dir, de, NULL);
if (error) {
printk(KERN_WARNING "%s: could not append to parent for %s\n",
__FUNCTION__, buf);
goto out;
}
devfsd_notify(de, DEVFSD_NOTIFY_REGISTERED);
out:
devfs_put(dir);
return error;
}
int devfs_mk_bdev(dev_t dev, umode_t mode, const char *fmt, ...)
{
va_list args;
if (!S_ISBLK(mode)) {
printk(KERN_WARNING "%s: invalide mode (%u) for %s\n",
__FUNCTION__, mode, fmt);
return -EINVAL;
}
va_start(args, fmt);
return devfs_mk_dev(dev, mode, fmt, args);
}
EXPORT_SYMBOL(devfs_mk_bdev);
int devfs_mk_cdev(dev_t dev, umode_t mode, const char *fmt, ...)
{
va_list args;
if (!S_ISCHR(mode)) {
printk(KERN_WARNING "%s: invalide mode (%u) for %s\n",
__FUNCTION__, mode, fmt);
return -EINVAL;
}
va_start(args, fmt);
return devfs_mk_dev(dev, mode, fmt, args);
}
EXPORT_SYMBOL(devfs_mk_cdev);
/**
* _devfs_unhook - Unhook a device entry from its parents list
* @de: The entry to unhook.
*
* Returns %TRUE if the entry was unhooked, else %FALSE if it was
* previously unhooked.
* The caller must have a write lock on the parent directory.
*/
static int _devfs_unhook(struct devfs_entry *de)
{
struct devfs_entry *parent;
if (!de || (de->prev == de))
return FALSE;
parent = de->parent;
if (de->prev == NULL)
parent->u.dir.first = de->next;
else
de->prev->next = de->next;
if (de->next == NULL)
parent->u.dir.last = de->prev;
else
de->next->prev = de->prev;
de->prev = de; /* Indicate we're unhooked */
de->next = NULL; /* Force early termination for <devfs_readdir> */
return TRUE;
} /* End Function _devfs_unhook */
/**
* _devfs_unregister - Unregister a device entry from its parent.
* @dir: The parent directory.
* @de: The entry to unregister.
*
* The caller must have a write lock on the parent directory, which is
* unlocked by this function.
*/
static void _devfs_unregister(struct devfs_entry *dir, struct devfs_entry *de)
{
int unhooked = _devfs_unhook(de);
write_unlock(&dir->u.dir.lock);
if (!unhooked)
return;
devfs_get(dir);
devfsd_notify(de, DEVFSD_NOTIFY_UNREGISTERED);
free_dentry(de);
devfs_put(dir);
if (!S_ISDIR(de->mode))
return;
while (TRUE) { /* Recursively unregister: this is a stack chomper */
struct devfs_entry *child;
write_lock(&de->u.dir.lock);
de->u.dir.no_more_additions = TRUE;
child = de->u.dir.first;
VERIFY_ENTRY(child);
_devfs_unregister(de, child);
if (!child)
break;
DPRINTK(DEBUG_UNREGISTER, "(%s): child: %p refcount: %d\n",
child->name, child, atomic_read(&child->refcount));
devfs_put(child);
}
} /* End Function _devfs_unregister */
static int devfs_do_symlink(devfs_handle_t dir, const char *name,
const char *link, devfs_handle_t * handle)
{
int err;
unsigned int linklength;
char *newlink;
struct devfs_entry *de;
if (handle != NULL)
*handle = NULL;
if (name == NULL) {
PRINTK("(): NULL name pointer\n");
return -EINVAL;
}
if (link == NULL) {
PRINTK("(%s): NULL link pointer\n", name);
return -EINVAL;
}
linklength = strlen(link);
if ((newlink = kmalloc(linklength + 1, GFP_KERNEL)) == NULL)
return -ENOMEM;
memcpy(newlink, link, linklength);
newlink[linklength] = '\0';
if ((de = _devfs_prepare_leaf(&dir, name, S_IFLNK | S_IRUGO | S_IXUGO))
== NULL) {
PRINTK("(%s): could not prepare leaf\n", name);
kfree(newlink);
return -ENOTDIR;
}
de->info = NULL;
de->u.symlink.linkname = newlink;
de->u.symlink.length = linklength;
if ((err = _devfs_append_entry(dir, de, NULL)) != 0) {
PRINTK("(%s): could not append to parent, err: %d\n", name,
err);
devfs_put(dir);
return err;
}
devfs_put(dir);
#ifdef CONFIG_DEVFS_DEBUG
spin_lock(&stat_lock);
stat_num_bytes += linklength + 1;
spin_unlock(&stat_lock);
#endif
if (handle != NULL)
*handle = de;
return 0;
} /* End Function devfs_do_symlink */
/**
* devfs_mk_symlink Create a symbolic link in the devfs namespace.
* @from: The name of the entry.
* @to: Name of the destination
*
* Returns 0 on success, else a negative error code is returned.
*/
int devfs_mk_symlink(const char *from, const char *to)
{
devfs_handle_t de;
int err;
err = devfs_do_symlink(NULL, from, to, &de);
if (!err) {
de->vfs = TRUE;
devfsd_notify(de, DEVFSD_NOTIFY_REGISTERED);
}
return err;
}
/**
* devfs_mk_dir - Create a directory in the devfs namespace.
* new name is relative to the root of the devfs.
* @fmt: The name of the entry.
*
* Use of this function is optional. The devfs_register() function
* will automatically create intermediate directories as needed. This function
* is provided for efficiency reasons, as it provides a handle to a directory.
* On failure %NULL is returned.
*/
int devfs_mk_dir(const char *fmt, ...)
{
struct devfs_entry *dir = NULL, *de = NULL, *old;
char buf[64];
va_list args;
int error, n;
va_start(args, fmt);
n = vsnprintf(buf, 64, fmt, args);
if (n >= 64 || !buf[0]) {
printk(KERN_WARNING "%s: invalid argument.", __FUNCTION__);
return -EINVAL;
}
de = _devfs_prepare_leaf(&dir, buf, MODE_DIR);
if (!de) {
PRINTK("(%s): could not prepare leaf\n", buf);
return -EINVAL;
}
error = _devfs_append_entry(dir, de, &old);
if (error == -EEXIST && S_ISDIR(old->mode)) {
/*
* devfs_mk_dir() of an already-existing directory will
* return success.
*/
error = 0;
goto out_put;
} else if (error) {
PRINTK("(%s): could not append to dir: %p \"%s\"\n",
buf, dir, dir->name);
devfs_put(old);
goto out_put;
}
devfsd_notify(de, DEVFSD_NOTIFY_REGISTERED);
out_put:
devfs_put(dir);
return error;
}
void devfs_remove(const char *fmt, ...)
{
char buf[64];
va_list args;
int n;
va_start(args, fmt);
n = vsnprintf(buf, sizeof(buf), fmt, args);
if (n < sizeof(buf) && buf[0]) {
devfs_handle_t de = _devfs_find_entry(NULL, buf, 0);
if (!de) {
printk(KERN_ERR "%s: %s not found, cannot remove\n",
__FUNCTION__, buf);
dump_stack();
return;
}
write_lock(&de->parent->u.dir.lock);
_devfs_unregister(de->parent, de);
devfs_put(de);
devfs_put(de);
}
}
/**
* devfs_generate_path - Generate a pathname for an entry, relative to the devfs root.
* @de: The devfs entry.
* @path: The buffer to write the pathname to. The pathname and '\0'
* terminator will be written at the end of the buffer.
* @buflen: The length of the buffer.
*
* Returns the offset in the buffer where the pathname starts on success,
* else a negative error code.
*/
static int devfs_generate_path(devfs_handle_t de, char *path, int buflen)
{
int pos;
#define NAMEOF(de) ( (de)->mode ? (de)->name : (de)->u.name )
if (de == NULL)
return -EINVAL;
VERIFY_ENTRY(de);
if (de->namelen >= buflen)
return -ENAMETOOLONG; /* Must be first */
path[buflen - 1] = '\0';
if (de->parent == NULL)
return buflen - 1; /* Don't prepend root */
pos = buflen - de->namelen - 1;
memcpy(path + pos, NAMEOF(de), de->namelen);
for (de = de->parent; de->parent != NULL; de = de->parent) {
if (pos - de->namelen - 1 < 0)
return -ENAMETOOLONG;
path[--pos] = '/';
pos -= de->namelen;
memcpy(path + pos, NAMEOF(de), de->namelen);
}
return pos;
} /* End Function devfs_generate_path */
/**
* devfs_setup - Process kernel boot options.
* @str: The boot options after the "devfs=".
*/
static int __init devfs_setup(char *str)
{
static struct {
char *name;
unsigned int mask;
unsigned int *opt;
} devfs_options_tab[] __initdata = {
#ifdef CONFIG_DEVFS_DEBUG
{
"dall", DEBUG_ALL, &devfs_debug_init}, {
"dmod", DEBUG_MODULE_LOAD, &devfs_debug_init}, {
"dreg", DEBUG_REGISTER, &devfs_debug_init}, {
"dunreg", DEBUG_UNREGISTER, &devfs_debug_init}, {
"dfree", DEBUG_FREE, &devfs_debug_init}, {
"diget", DEBUG_I_GET, &devfs_debug_init}, {
"dchange", DEBUG_SET_FLAGS, &devfs_debug_init}, {
"dsread", DEBUG_S_READ, &devfs_debug_init}, {
"dichange", DEBUG_I_CHANGE, &devfs_debug_init}, {
"dimknod", DEBUG_I_MKNOD, &devfs_debug_init}, {
"dilookup", DEBUG_I_LOOKUP, &devfs_debug_init}, {
"diunlink", DEBUG_I_UNLINK, &devfs_debug_init},
#endif /* CONFIG_DEVFS_DEBUG */
{
"mount", OPTION_MOUNT, &boot_options}, {
NULL, 0, NULL}
};
while ((*str != '\0') && !isspace(*str)) {
int i, found = 0, invert = 0;
if (strncmp(str, "no", 2) == 0) {
invert = 1;
str += 2;
}
for (i = 0; devfs_options_tab[i].name != NULL; i++) {
int len = strlen(devfs_options_tab[i].name);
if (strncmp(str, devfs_options_tab[i].name, len) == 0) {
if (invert)
*devfs_options_tab[i].opt &=
~devfs_options_tab[i].mask;
else
*devfs_options_tab[i].opt |=
devfs_options_tab[i].mask;
str += len;
found = 1;
break;
}
}
if (!found)
return 0; /* No match */
if (*str != ',')
return 0; /* No more options */
++str;
}
return 1;
} /* End Function devfs_setup */
__setup("devfs=", devfs_setup);
EXPORT_SYMBOL(devfs_mk_dir);
EXPORT_SYMBOL(devfs_remove);
/**
* try_modload - Notify devfsd of an inode lookup by a non-devfsd process.
* @parent: The parent devfs entry.
* @fs_info: The filesystem info.
* @name: The device name.
* @namelen: The number of characters in @name.
* @buf: A working area that will be used. This must not go out of scope
* until devfsd is idle again.
*
* Returns 0 on success (event was queued), else a negative error code.
*/
static int try_modload(struct devfs_entry *parent, struct fs_info *fs_info,
const char *name, unsigned namelen,
struct devfs_entry *buf)
{
if (!(fs_info->devfsd_event_mask & (1 << DEVFSD_NOTIFY_LOOKUP)))
return -ENOENT;
if (is_devfsd_or_child(fs_info))
return -ENOENT;
memset(buf, 0, sizeof *buf);
atomic_set(&buf->refcount, 1);
buf->parent = parent;
buf->namelen = namelen;
buf->u.name = name;
WRITE_ENTRY_MAGIC(buf, MAGIC_VALUE);
if (!devfsd_notify_de(buf, DEVFSD_NOTIFY_LOOKUP, 0,
current->euid, current->egid, fs_info))
return -ENOENT;
/* Possible success: event has been queued */
return 0;
} /* End Function try_modload */
/* Superblock operations follow */
static struct inode_operations devfs_iops;
static struct inode_operations devfs_dir_iops;
static struct file_operations devfs_fops;
static struct file_operations devfs_dir_fops;
static struct inode_operations devfs_symlink_iops;
static int devfs_notify_change(struct dentry *dentry, struct iattr *iattr)
{
int retval;
struct devfs_entry *de;
struct inode *inode = dentry->d_inode;
struct fs_info *fs_info = inode->i_sb->s_fs_info;
de = get_devfs_entry_from_vfs_inode(inode);
if (de == NULL)
return -ENODEV;
retval = inode_change_ok(inode, iattr);
if (retval != 0)
return retval;
retval = inode_setattr(inode, iattr);
if (retval != 0)
return retval;
DPRINTK(DEBUG_I_CHANGE, "(%d): VFS inode: %p devfs_entry: %p\n",
(int)inode->i_ino, inode, de);
DPRINTK(DEBUG_I_CHANGE, "(): mode: 0%o uid: %d gid: %d\n",
(int)inode->i_mode, (int)inode->i_uid, (int)inode->i_gid);
/* Inode is not on hash chains, thus must save permissions here rather
than in a write_inode() method */
de->mode = inode->i_mode;
de->inode.uid = inode->i_uid;
de->inode.gid = inode->i_gid;
de->inode.atime = inode->i_atime;
de->inode.mtime = inode->i_mtime;
de->inode.ctime = inode->i_ctime;
if ((iattr->ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID)) &&
!is_devfsd_or_child(fs_info))
devfsd_notify_de(de, DEVFSD_NOTIFY_CHANGE, inode->i_mode,
inode->i_uid, inode->i_gid, fs_info);
return 0;
} /* End Function devfs_notify_change */
static struct super_operations devfs_sops = {
.drop_inode = generic_delete_inode,
.statfs = simple_statfs,
};
/**
* _devfs_get_vfs_inode - Get a VFS inode.
* @sb: The super block.
* @de: The devfs inode.
* @dentry: The dentry to register with the devfs inode.
*
* Returns the inode on success, else %NULL. An implicit devfs_get() is
* performed if the inode is created.
*/
static struct inode *_devfs_get_vfs_inode(struct super_block *sb,
struct devfs_entry *de,
struct dentry *dentry)
{
struct inode *inode;
if (de->prev == de)
return NULL; /* Quick check to see if unhooked */
if ((inode = new_inode(sb)) == NULL) {
PRINTK("(%s): new_inode() failed, de: %p\n", de->name, de);
return NULL;
}
if (de->parent) {
read_lock(&de->parent->u.dir.lock);
if (de->prev != de)
de->inode.dentry = dentry; /* Not unhooked */
read_unlock(&de->parent->u.dir.lock);
} else
de->inode.dentry = dentry; /* Root: no locking needed */
if (de->inode.dentry != dentry) { /* Must have been unhooked */
iput(inode);
return NULL;
}
/* FIXME where is devfs_put? */
inode->u.generic_ip = devfs_get(de);
inode->i_ino = de->inode.ino;
DPRINTK(DEBUG_I_GET, "(%d): VFS inode: %p devfs_entry: %p\n",
(int)inode->i_ino, inode, de);
inode->i_blocks = 0;
inode->i_blksize = FAKE_BLOCK_SIZE;
inode->i_op = &devfs_iops;
inode->i_mode = de->mode;
if (S_ISDIR(de->mode)) {
inode->i_op = &devfs_dir_iops;
inode->i_fop = &devfs_dir_fops;
} else if (S_ISLNK(de->mode)) {
inode->i_op = &devfs_symlink_iops;
inode->i_size = de->u.symlink.length;
} else if (S_ISCHR(de->mode) || S_ISBLK(de->mode)) {
init_special_inode(inode, de->mode, de->u.dev);
} else if (S_ISFIFO(de->mode) || S_ISSOCK(de->mode)) {
init_special_inode(inode, de->mode, 0);
} else {
PRINTK("(%s): unknown mode %o de: %p\n",
de->name, de->mode, de);
iput(inode);
devfs_put(de);
return NULL;
}
inode->i_uid = de->inode.uid;
inode->i_gid = de->inode.gid;
inode->i_atime = de->inode.atime;
inode->i_mtime = de->inode.mtime;
inode->i_ctime = de->inode.ctime;
DPRINTK(DEBUG_I_GET, "(): mode: 0%o uid: %d gid: %d\n",
(int)inode->i_mode, (int)inode->i_uid, (int)inode->i_gid);
return inode;
} /* End Function _devfs_get_vfs_inode */
/* File operations for device entries follow */
static int devfs_readdir(struct file *file, void *dirent, filldir_t filldir)
{
int err, count;
int stored = 0;
struct fs_info *fs_info;
struct devfs_entry *parent, *de, *next = NULL;
struct inode *inode = file->f_dentry->d_inode;
fs_info = inode->i_sb->s_fs_info;
parent = get_devfs_entry_from_vfs_inode(file->f_dentry->d_inode);
if ((long)file->f_pos < 0)
return -EINVAL;
DPRINTK(DEBUG_F_READDIR, "(%s): fs_info: %p pos: %ld\n",
parent->name, fs_info, (long)file->f_pos);
switch ((long)file->f_pos) {
case 0:
err = (*filldir) (dirent, "..", 2, file->f_pos,
parent_ino(file->f_dentry), DT_DIR);
if (err == -EINVAL)
break;
if (err < 0)
return err;
file->f_pos++;
++stored;
/* Fall through */
case 1:
err =
(*filldir) (dirent, ".", 1, file->f_pos, inode->i_ino,
DT_DIR);
if (err == -EINVAL)
break;
if (err < 0)
return err;
file->f_pos++;
++stored;
/* Fall through */
default:
/* Skip entries */
count = file->f_pos - 2;
read_lock(&parent->u.dir.lock);
for (de = parent->u.dir.first; de && (count > 0); de = de->next)
--count;
devfs_get(de);
read_unlock(&parent->u.dir.lock);
/* Now add all remaining entries */
while (de) {
err = (*filldir) (dirent, de->name, de->namelen,
file->f_pos, de->inode.ino,
de->mode >> 12);
if (err < 0)
devfs_put(de);
else {
file->f_pos++;
++stored;
}
if (err == -EINVAL)
break;
if (err < 0)
return err;
read_lock(&parent->u.dir.lock);
next = devfs_get(de->next);
read_unlock(&parent->u.dir.lock);
devfs_put(de);
de = next;
}
break;
}
return stored;
} /* End Function devfs_readdir */
/* Open devfs specific special files */
static int devfs_open(struct inode *inode, struct file *file)
{
int err;
int minor = MINOR(inode->i_rdev);
struct file_operations *old_fops, *new_fops;
switch (minor) {
case 0: /* /dev/.devfsd */
new_fops = fops_get(&devfsd_fops);
break;
#ifdef CONFIG_DEVFS_DEBUG
case 1: /* /dev/.stat */
new_fops = fops_get(&stat_fops);
break;
#endif
default:
return -ENODEV;
}
if (new_fops == NULL)
return -ENODEV;
old_fops = file->f_op;
file->f_op = new_fops;
err = new_fops->open ? new_fops->open(inode, file) : 0;
if (err) {
file->f_op = old_fops;
fops_put(new_fops);
} else
fops_put(old_fops);
return err;
} /* End Function devfs_open */
static struct file_operations devfs_fops = {
.open = devfs_open,
};
static struct file_operations devfs_dir_fops = {
.read = generic_read_dir,
.readdir = devfs_readdir,
};
/* Dentry operations for device entries follow */
/**
* devfs_d_release - Callback for when a dentry is freed.
* @dentry: The dentry.
*/
static void devfs_d_release(struct dentry *dentry)
{
DPRINTK(DEBUG_D_RELEASE, "(%p): inode: %p\n", dentry, dentry->d_inode);
} /* End Function devfs_d_release */
/**
* devfs_d_iput - Callback for when a dentry loses its inode.
* @dentry: The dentry.
* @inode: The inode.
*/
static void devfs_d_iput(struct dentry *dentry, struct inode *inode)
{
struct devfs_entry *de;
de = get_devfs_entry_from_vfs_inode(inode);
DPRINTK(DEBUG_D_IPUT,
"(%s): dentry: %p inode: %p de: %p de->dentry: %p\n", de->name,
dentry, inode, de, de->inode.dentry);
if (de->inode.dentry && (de->inode.dentry != dentry))
OOPS("(%s): de: %p dentry: %p de->dentry: %p\n",
de->name, de, dentry, de->inode.dentry);
de->inode.dentry = NULL;
iput(inode);
devfs_put(de);
} /* End Function devfs_d_iput */
static int devfs_d_delete(struct dentry *dentry);
static struct dentry_operations devfs_dops = {
.d_delete = devfs_d_delete,
.d_release = devfs_d_release,
.d_iput = devfs_d_iput,
};
static int devfs_d_revalidate_wait(struct dentry *dentry, struct nameidata *);
static struct dentry_operations devfs_wait_dops = {
.d_delete = devfs_d_delete,
.d_release = devfs_d_release,
.d_iput = devfs_d_iput,
.d_revalidate = devfs_d_revalidate_wait,
};
/**
* devfs_d_delete - Callback for when all files for a dentry are closed.
* @dentry: The dentry.
*/
static int devfs_d_delete(struct dentry *dentry)
{
struct inode *inode = dentry->d_inode;
if (dentry->d_op == &devfs_wait_dops)
dentry->d_op = &devfs_dops;
/* Unhash dentry if negative (has no inode) */
if (inode == NULL) {
DPRINTK(DEBUG_D_DELETE, "(%p): dropping negative dentry\n",
dentry);
return 1;
}
return 0;
} /* End Function devfs_d_delete */
struct devfs_lookup_struct {
devfs_handle_t de;
wait_queue_head_t wait_queue;
};
/* XXX: this doesn't handle the case where we got a negative dentry
but a devfs entry has been registered in the meanwhile */
static int devfs_d_revalidate_wait(struct dentry *dentry, struct nameidata *nd)
{
struct inode *dir = dentry->d_parent->d_inode;
struct fs_info *fs_info = dir->i_sb->s_fs_info;
devfs_handle_t parent = get_devfs_entry_from_vfs_inode(dir);
struct devfs_lookup_struct *lookup_info = dentry->d_fsdata;
DECLARE_WAITQUEUE(wait, current);
int need_lock;
/*
* FIXME HACK
*
* make sure that
* d_instantiate always runs under lock
* we release i_mutex lock before going to sleep
*
* unfortunately sometimes d_revalidate is called with
* and sometimes without i_mutex lock held. The following checks
* attempt to deduce when we need to add (and drop resp.) lock
* here. This relies on current (2.6.2) calling coventions:
*
* lookup_hash is always run under i_mutex and is passing NULL
* as nd
*
* open(...,O_CREATE,...) calls _lookup_hash under i_mutex
* and sets flags to LOOKUP_OPEN|LOOKUP_CREATE
*
* all other invocations of ->d_revalidate seem to happen
* outside of i_mutex
*/
need_lock = nd &&
(!(nd->flags & LOOKUP_CREATE) || (nd->flags & LOOKUP_PARENT));
if (need_lock)
mutex_lock(&dir->i_mutex);
if (is_devfsd_or_child(fs_info)) {
devfs_handle_t de = lookup_info->de;
struct inode *inode;
DPRINTK(DEBUG_I_LOOKUP,
"(%s): dentry: %p inode: %p de: %p by: \"%s\"\n",
dentry->d_name.name, dentry, dentry->d_inode, de,
current->comm);
if (dentry->d_inode)
goto out;
if (de == NULL) {
read_lock(&parent->u.dir.lock);
de = _devfs_search_dir(parent, dentry->d_name.name,
dentry->d_name.len);
read_unlock(&parent->u.dir.lock);
if (de == NULL)
goto out;
lookup_info->de = de;
}
/* Create an inode, now that the driver information is available */
inode = _devfs_get_vfs_inode(dir->i_sb, de, dentry);
if (!inode)
goto out;
DPRINTK(DEBUG_I_LOOKUP,
"(%s): new VFS inode(%u): %p de: %p by: \"%s\"\n",
de->name, de->inode.ino, inode, de, current->comm);
d_instantiate(dentry, inode);
goto out;
}
if (lookup_info == NULL)
goto out; /* Early termination */
read_lock(&parent->u.dir.lock);
if (dentry->d_fsdata) {
set_current_state(TASK_UNINTERRUPTIBLE);
add_wait_queue(&lookup_info->wait_queue, &wait);
read_unlock(&parent->u.dir.lock);
/* at this point it is always (hopefully) locked */
mutex_unlock(&dir->i_mutex);
schedule();
mutex_lock(&dir->i_mutex);
/*
* This does not need nor should remove wait from wait_queue.
* Wait queue head is never reused - nothing is ever added to it
* after all waiters have been waked up and head itself disappears
* very soon after it. Moreover it is local variable on stack that
* is likely to have already disappeared so any reference to it
* at this point is buggy.
*/
} else
read_unlock(&parent->u.dir.lock);
out:
if (need_lock)
mutex_unlock(&dir->i_mutex);
return 1;
} /* End Function devfs_d_revalidate_wait */
/* Inode operations for device entries follow */
static struct dentry *devfs_lookup(struct inode *dir, struct dentry *dentry,
struct nameidata *nd)
{
struct devfs_entry tmp; /* Must stay in scope until devfsd idle again */
struct devfs_lookup_struct lookup_info;
struct fs_info *fs_info = dir->i_sb->s_fs_info;
struct devfs_entry *parent, *de;
struct inode *inode;
struct dentry *retval = NULL;
/* Set up the dentry operations before anything else, to ensure cleaning
up on any error */
dentry->d_op = &devfs_dops;
/* First try to get the devfs entry for this directory */
parent = get_devfs_entry_from_vfs_inode(dir);
DPRINTK(DEBUG_I_LOOKUP, "(%s): dentry: %p parent: %p by: \"%s\"\n",
dentry->d_name.name, dentry, parent, current->comm);
if (parent == NULL)
return ERR_PTR(-ENOENT);
read_lock(&parent->u.dir.lock);
de = _devfs_search_dir(parent, dentry->d_name.name, dentry->d_name.len);
read_unlock(&parent->u.dir.lock);
lookup_info.de = de;
init_waitqueue_head(&lookup_info.wait_queue);
dentry->d_fsdata = &lookup_info;
if (de == NULL) { /* Try with devfsd. For any kind of failure, leave a negative dentry
so someone else can deal with it (in the case where the sysadmin
does a mknod()). It's important to do this before hashing the
dentry, so that the devfsd queue is filled before revalidates
can start */
if (try_modload(parent, fs_info, dentry->d_name.name, dentry->d_name.len, &tmp) < 0) { /* Lookup event was not queued to devfsd */
d_add(dentry, NULL);
return NULL;
}
}
dentry->d_op = &devfs_wait_dops;
d_add(dentry, NULL); /* Open the floodgates */
/* Unlock directory semaphore, which will release any waiters. They
will get the hashed dentry, and may be forced to wait for
revalidation */
mutex_unlock(&dir->i_mutex);
wait_for_devfsd_finished(fs_info); /* If I'm not devfsd, must wait */
mutex_lock(&dir->i_mutex); /* Grab it again because them's the rules */
de = lookup_info.de;
/* If someone else has been so kind as to make the inode, we go home
early */
if (dentry->d_inode)
goto out;
if (de == NULL) {
read_lock(&parent->u.dir.lock);
de = _devfs_search_dir(parent, dentry->d_name.name,
dentry->d_name.len);
read_unlock(&parent->u.dir.lock);
if (de == NULL)
goto out;
/* OK, there's an entry now, but no VFS inode yet */
}
/* Create an inode, now that the driver information is available */
inode = _devfs_get_vfs_inode(dir->i_sb, de, dentry);
if (!inode) {
retval = ERR_PTR(-ENOMEM);
goto out;
}
DPRINTK(DEBUG_I_LOOKUP,
"(%s): new VFS inode(%u): %p de: %p by: \"%s\"\n", de->name,
de->inode.ino, inode, de, current->comm);
d_instantiate(dentry, inode);
out:
write_lock(&parent->u.dir.lock);
dentry->d_op = &devfs_dops;
dentry->d_fsdata = NULL;
wake_up(&lookup_info.wait_queue);
write_unlock(&parent->u.dir.lock);
devfs_put(de);
return retval;
} /* End Function devfs_lookup */
static int devfs_unlink(struct inode *dir, struct dentry *dentry)
{
int unhooked;
struct devfs_entry *de;
struct inode *inode = dentry->d_inode;
struct fs_info *fs_info = dir->i_sb->s_fs_info;
de = get_devfs_entry_from_vfs_inode(inode);
DPRINTK(DEBUG_I_UNLINK, "(%s): de: %p\n", dentry->d_name.name, de);
if (de == NULL)
return -ENOENT;
if (!de->vfs)
return -EPERM;
write_lock(&de->parent->u.dir.lock);
unhooked = _devfs_unhook(de);
write_unlock(&de->parent->u.dir.lock);
if (!unhooked)
return -ENOENT;
if (!is_devfsd_or_child(fs_info))
devfsd_notify_de(de, DEVFSD_NOTIFY_DELETE, inode->i_mode,
inode->i_uid, inode->i_gid, fs_info);
free_dentry(de);
devfs_put(de);
return 0;
} /* End Function devfs_unlink */
static int devfs_symlink(struct inode *dir, struct dentry *dentry,
const char *symname)
{
int err;
struct fs_info *fs_info = dir->i_sb->s_fs_info;
struct devfs_entry *parent, *de;
struct inode *inode;
/* First try to get the devfs entry for this directory */
parent = get_devfs_entry_from_vfs_inode(dir);
if (parent == NULL)
return -ENOENT;
err = devfs_do_symlink(parent, dentry->d_name.name, symname, &de);
DPRINTK(DEBUG_DISABLED, "(%s): errcode from <devfs_do_symlink>: %d\n",
dentry->d_name.name, err);
if (err < 0)
return err;
de->vfs = TRUE;
de->inode.uid = current->euid;
de->inode.gid = current->egid;
de->inode.atime = CURRENT_TIME;
de->inode.mtime = CURRENT_TIME;
de->inode.ctime = CURRENT_TIME;
if ((inode = _devfs_get_vfs_inode(dir->i_sb, de, dentry)) == NULL)
return -ENOMEM;
DPRINTK(DEBUG_DISABLED, "(%s): new VFS inode(%u): %p dentry: %p\n",
dentry->d_name.name, de->inode.ino, inode, dentry);
d_instantiate(dentry, inode);
if (!is_devfsd_or_child(fs_info))
devfsd_notify_de(de, DEVFSD_NOTIFY_CREATE, inode->i_mode,
inode->i_uid, inode->i_gid, fs_info);
return 0;
} /* End Function devfs_symlink */
static int devfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
{
int err;
struct fs_info *fs_info = dir->i_sb->s_fs_info;
struct devfs_entry *parent, *de;
struct inode *inode;
mode = (mode & ~S_IFMT) | S_IFDIR; /* VFS doesn't pass S_IFMT part */
parent = get_devfs_entry_from_vfs_inode(dir);
if (parent == NULL)
return -ENOENT;
de = _devfs_alloc_entry(dentry->d_name.name, dentry->d_name.len, mode);
if (!de)
return -ENOMEM;
de->vfs = TRUE;
if ((err = _devfs_append_entry(parent, de, NULL)) != 0)
return err;
de->inode.uid = current->euid;
de->inode.gid = current->egid;
de->inode.atime = CURRENT_TIME;
de->inode.mtime = CURRENT_TIME;
de->inode.ctime = CURRENT_TIME;
if ((inode = _devfs_get_vfs_inode(dir->i_sb, de, dentry)) == NULL)
return -ENOMEM;
DPRINTK(DEBUG_DISABLED, "(%s): new VFS inode(%u): %p dentry: %p\n",
dentry->d_name.name, de->inode.ino, inode, dentry);
d_instantiate(dentry, inode);
if (!is_devfsd_or_child(fs_info))
devfsd_notify_de(de, DEVFSD_NOTIFY_CREATE, inode->i_mode,
inode->i_uid, inode->i_gid, fs_info);
return 0;
} /* End Function devfs_mkdir */
static int devfs_rmdir(struct inode *dir, struct dentry *dentry)
{
int err = 0;
struct devfs_entry *de;
struct fs_info *fs_info = dir->i_sb->s_fs_info;
struct inode *inode = dentry->d_inode;
if (dir->i_sb->s_fs_info != inode->i_sb->s_fs_info)
return -EINVAL;
de = get_devfs_entry_from_vfs_inode(inode);
if (de == NULL)
return -ENOENT;
if (!S_ISDIR(de->mode))
return -ENOTDIR;
if (!de->vfs)
return -EPERM;
/* First ensure the directory is empty and will stay that way */
write_lock(&de->u.dir.lock);
if (de->u.dir.first)
err = -ENOTEMPTY;
else
de->u.dir.no_more_additions = TRUE;
write_unlock(&de->u.dir.lock);
if (err)
return err;
/* Now unhook the directory from its parent */
write_lock(&de->parent->u.dir.lock);
if (!_devfs_unhook(de))
err = -ENOENT;
write_unlock(&de->parent->u.dir.lock);
if (err)
return err;
if (!is_devfsd_or_child(fs_info))
devfsd_notify_de(de, DEVFSD_NOTIFY_DELETE, inode->i_mode,
inode->i_uid, inode->i_gid, fs_info);
free_dentry(de);
devfs_put(de);
return 0;
} /* End Function devfs_rmdir */
static int devfs_mknod(struct inode *dir, struct dentry *dentry, int mode,
dev_t rdev)
{
int err;
struct fs_info *fs_info = dir->i_sb->s_fs_info;
struct devfs_entry *parent, *de;
struct inode *inode;
DPRINTK(DEBUG_I_MKNOD, "(%s): mode: 0%o dev: %u:%u\n",
dentry->d_name.name, mode, MAJOR(rdev), MINOR(rdev));
parent = get_devfs_entry_from_vfs_inode(dir);
if (parent == NULL)
return -ENOENT;
de = _devfs_alloc_entry(dentry->d_name.name, dentry->d_name.len, mode);
if (!de)
return -ENOMEM;
de->vfs = TRUE;
if (S_ISCHR(mode) || S_ISBLK(mode))
de->u.dev = rdev;
if ((err = _devfs_append_entry(parent, de, NULL)) != 0)
return err;
de->inode.uid = current->euid;
de->inode.gid = current->egid;
de->inode.atime = CURRENT_TIME;
de->inode.mtime = CURRENT_TIME;
de->inode.ctime = CURRENT_TIME;
if ((inode = _devfs_get_vfs_inode(dir->i_sb, de, dentry)) == NULL)
return -ENOMEM;
DPRINTK(DEBUG_I_MKNOD, ": new VFS inode(%u): %p dentry: %p\n",
de->inode.ino, inode, dentry);
d_instantiate(dentry, inode);
if (!is_devfsd_or_child(fs_info))
devfsd_notify_de(de, DEVFSD_NOTIFY_CREATE, inode->i_mode,
inode->i_uid, inode->i_gid, fs_info);
return 0;
} /* End Function devfs_mknod */
static void *devfs_follow_link(struct dentry *dentry, struct nameidata *nd)
{
struct devfs_entry *p = get_devfs_entry_from_vfs_inode(dentry->d_inode);
nd_set_link(nd, p ? p->u.symlink.linkname : ERR_PTR(-ENODEV));
return NULL;
} /* End Function devfs_follow_link */
static struct inode_operations devfs_iops = {
.setattr = devfs_notify_change,
};
static struct inode_operations devfs_dir_iops = {
.lookup = devfs_lookup,
.unlink = devfs_unlink,
.symlink = devfs_symlink,
.mkdir = devfs_mkdir,
.rmdir = devfs_rmdir,
.mknod = devfs_mknod,
.setattr = devfs_notify_change,
};
static struct inode_operations devfs_symlink_iops = {
.readlink = generic_readlink,
.follow_link = devfs_follow_link,
.setattr = devfs_notify_change,
};
static int devfs_fill_super(struct super_block *sb, void *data, int silent)
{
struct inode *root_inode = NULL;
if (_devfs_get_root_entry() == NULL)
goto out_no_root;
atomic_set(&fs_info.devfsd_overrun_count, 0);
init_waitqueue_head(&fs_info.devfsd_wait_queue);
init_waitqueue_head(&fs_info.revalidate_wait_queue);
fs_info.sb = sb;
sb->s_fs_info = &fs_info;
sb->s_blocksize = 1024;
sb->s_blocksize_bits = 10;
sb->s_magic = DEVFS_SUPER_MAGIC;
sb->s_op = &devfs_sops;
sb->s_time_gran = 1;
if ((root_inode = _devfs_get_vfs_inode(sb, root_entry, NULL)) == NULL)
goto out_no_root;
sb->s_root = d_alloc_root(root_inode);
if (!sb->s_root)
goto out_no_root;
DPRINTK(DEBUG_S_READ, "(): made devfs ptr: %p\n", sb->s_fs_info);
return 0;
out_no_root:
PRINTK("(): get root inode failed\n");
if (root_inode)
iput(root_inode);
return -EINVAL;
} /* End Function devfs_fill_super */
static struct super_block *devfs_get_sb(struct file_system_type *fs_type,
int flags, const char *dev_name,
void *data)
{
return get_sb_single(fs_type, flags, data, devfs_fill_super);
}
static struct file_system_type devfs_fs_type = {
.name = DEVFS_NAME,
.get_sb = devfs_get_sb,
.kill_sb = kill_anon_super,
};
/* File operations for devfsd follow */
static ssize_t devfsd_read(struct file *file, char __user *buf, size_t len,
loff_t * ppos)
{
int done = FALSE;
int ival;
loff_t pos, devname_offset, tlen, rpos;
devfs_handle_t de;
struct devfsd_buf_entry *entry;
struct fs_info *fs_info = file->f_dentry->d_inode->i_sb->s_fs_info;
struct devfsd_notify_struct *info = fs_info->devfsd_info;
DECLARE_WAITQUEUE(wait, current);
/* Verify the task has grabbed the queue */
if (fs_info->devfsd_task != current)
return -EPERM;
info->major = 0;
info->minor = 0;
/* Block for a new entry */
set_current_state(TASK_INTERRUPTIBLE);
add_wait_queue(&fs_info->devfsd_wait_queue, &wait);
while (devfsd_queue_empty(fs_info)) {
fs_info->devfsd_sleeping = TRUE;
wake_up(&fs_info->revalidate_wait_queue);
schedule();
fs_info->devfsd_sleeping = FALSE;
if (signal_pending(current)) {
remove_wait_queue(&fs_info->devfsd_wait_queue, &wait);
__set_current_state(TASK_RUNNING);
return -EINTR;
}
set_current_state(TASK_INTERRUPTIBLE);
}
remove_wait_queue(&fs_info->devfsd_wait_queue, &wait);
__set_current_state(TASK_RUNNING);
/* Now play with the data */
ival = atomic_read(&fs_info->devfsd_overrun_count);
info->overrun_count = ival;
entry = fs_info->devfsd_first_event;
info->type = entry->type;
info->mode = entry->mode;
info->uid = entry->uid;
info->gid = entry->gid;
de = entry->de;
if (S_ISCHR(de->mode) || S_ISBLK(de->mode)) {
info->major = MAJOR(de->u.dev);
info->minor = MINOR(de->u.dev);
}
pos = devfs_generate_path(de, info->devname, DEVFS_PATHLEN);
if (pos < 0)
return pos;
info->namelen = DEVFS_PATHLEN - pos - 1;
if (info->mode == 0)
info->mode = de->mode;
devname_offset = info->devname - (char *)info;
rpos = *ppos;
if (rpos < devname_offset) {
/* Copy parts of the header */
tlen = devname_offset - rpos;
if (tlen > len)
tlen = len;
if (copy_to_user(buf, (char *)info + rpos, tlen)) {
return -EFAULT;
}
rpos += tlen;
buf += tlen;
len -= tlen;
}
if ((rpos >= devname_offset) && (len > 0)) {
/* Copy the name */
tlen = info->namelen + 1;
if (tlen > len)
tlen = len;
else
done = TRUE;
if (copy_to_user
(buf, info->devname + pos + rpos - devname_offset, tlen)) {
return -EFAULT;
}
rpos += tlen;
}
tlen = rpos - *ppos;
if (done) {
devfs_handle_t parent;
spin_lock(&fs_info->devfsd_buffer_lock);
fs_info->devfsd_first_event = entry->next;
if (entry->next == NULL)
fs_info->devfsd_last_event = NULL;
spin_unlock(&fs_info->devfsd_buffer_lock);
for (; de != NULL; de = parent) {
parent = de->parent;
devfs_put(de);
}
kmem_cache_free(devfsd_buf_cache, entry);
if (ival > 0)
atomic_sub(ival, &fs_info->devfsd_overrun_count);
*ppos = 0;
} else
*ppos = rpos;
return tlen;
} /* End Function devfsd_read */
static int devfsd_ioctl(struct inode *inode, struct file *file,
unsigned int cmd, unsigned long arg)
{
int ival;
struct fs_info *fs_info = inode->i_sb->s_fs_info;
switch (cmd) {
case DEVFSDIOC_GET_PROTO_REV:
ival = DEVFSD_PROTOCOL_REVISION_KERNEL;
if (copy_to_user((void __user *)arg, &ival, sizeof ival))
return -EFAULT;
break;
case DEVFSDIOC_SET_EVENT_MASK:
/* Ensure only one reader has access to the queue. This scheme will
work even if the global kernel lock were to be removed, because it
doesn't matter who gets in first, as long as only one gets it */
if (fs_info->devfsd_task == NULL) {
static DEFINE_SPINLOCK(lock);
if (!spin_trylock(&lock))
return -EBUSY;
if (fs_info->devfsd_task != NULL) { /* We lost the race... */
spin_unlock(&lock);
return -EBUSY;
}
fs_info->devfsd_task = current;
spin_unlock(&lock);
fs_info->devfsd_pgrp =
(process_group(current) ==
current->pid) ? process_group(current) : 0;
fs_info->devfsd_file = file;
fs_info->devfsd_info =
kmalloc(sizeof *fs_info->devfsd_info, GFP_KERNEL);
if (!fs_info->devfsd_info) {
devfsd_close(inode, file);
return -ENOMEM;
}
} else if (fs_info->devfsd_task != current)
return -EBUSY;
fs_info->devfsd_event_mask = arg; /* Let the masses come forth */
break;
case DEVFSDIOC_RELEASE_EVENT_QUEUE:
if (fs_info->devfsd_file != file)
return -EPERM;
return devfsd_close(inode, file);
/*break; */
#ifdef CONFIG_DEVFS_DEBUG
case DEVFSDIOC_SET_DEBUG_MASK:
if (copy_from_user(&ival, (void __user *)arg, sizeof ival))
return -EFAULT;
devfs_debug = ival;
break;
#endif
default:
return -ENOIOCTLCMD;
}
return 0;
} /* End Function devfsd_ioctl */
static int devfsd_close(struct inode *inode, struct file *file)
{
struct devfsd_buf_entry *entry, *next;
struct fs_info *fs_info = inode->i_sb->s_fs_info;
if (fs_info->devfsd_file != file)
return 0;
fs_info->devfsd_event_mask = 0;
fs_info->devfsd_file = NULL;
spin_lock(&fs_info->devfsd_buffer_lock);
entry = fs_info->devfsd_first_event;
fs_info->devfsd_first_event = NULL;
fs_info->devfsd_last_event = NULL;
kfree(fs_info->devfsd_info);
fs_info->devfsd_info = NULL;
spin_unlock(&fs_info->devfsd_buffer_lock);
fs_info->devfsd_pgrp = 0;
fs_info->devfsd_task = NULL;
wake_up(&fs_info->revalidate_wait_queue);
for (; entry; entry = next) {
next = entry->next;
kmem_cache_free(devfsd_buf_cache, entry);
}
return 0;
} /* End Function devfsd_close */
#ifdef CONFIG_DEVFS_DEBUG
static ssize_t stat_read(struct file *file, char __user *buf, size_t len,
loff_t * ppos)
{
ssize_t num;
char txt[80];
num = sprintf(txt, "Number of entries: %u number of bytes: %u\n",
stat_num_entries, stat_num_bytes) + 1;
if (*ppos >= num)
return 0;
if (*ppos + len > num)
len = num - *ppos;
if (copy_to_user(buf, txt + *ppos, len))
return -EFAULT;
*ppos += len;
return len;
} /* End Function stat_read */
#endif
static int __init init_devfs_fs(void)
{
int err;
int major;
struct devfs_entry *devfsd;
#ifdef CONFIG_DEVFS_DEBUG
struct devfs_entry *stat;
#endif
if (_devfs_get_root_entry() == NULL)
return -ENOMEM;
printk(KERN_INFO "%s: %s Richard Gooch (rgooch@atnf.csiro.au)\n",
DEVFS_NAME, DEVFS_VERSION);
devfsd_buf_cache = kmem_cache_create("devfsd_event",
sizeof(struct devfsd_buf_entry),
0, 0, NULL, NULL);
if (!devfsd_buf_cache)
OOPS("(): unable to allocate event slab\n");
#ifdef CONFIG_DEVFS_DEBUG
devfs_debug = devfs_debug_init;
printk(KERN_INFO "%s: devfs_debug: 0x%0x\n", DEVFS_NAME, devfs_debug);
#endif
printk(KERN_INFO "%s: boot_options: 0x%0x\n", DEVFS_NAME, boot_options);
/* register special device for devfsd communication */
major = register_chrdev(0, "devfs", &devfs_fops);
if (major < 0)
return major;
/* And create the entry for ".devfsd" */
devfsd = _devfs_alloc_entry(".devfsd", 0, S_IFCHR | S_IRUSR | S_IWUSR);
if (devfsd == NULL)
return -ENOMEM;
devfsd->u.dev = MKDEV(major, 0);
_devfs_append_entry(root_entry, devfsd, NULL);
#ifdef CONFIG_DEVFS_DEBUG
stat = _devfs_alloc_entry(".stat", 0, S_IFCHR | S_IRUGO);
if (stat == NULL)
return -ENOMEM;
stat->u.dev = MKDEV(major, 1);
_devfs_append_entry(root_entry, stat, NULL);
#endif
err = register_filesystem(&devfs_fs_type);
return err;
} /* End Function init_devfs_fs */
void __init mount_devfs_fs(void)
{
int err;
if (!(boot_options & OPTION_MOUNT))
return;
err = do_mount("none", "/dev", "devfs", 0, NULL);
if (err == 0)
printk(KERN_INFO "Mounted devfs on /dev\n");
else
PRINTK("(): unable to mount devfs, err: %d\n", err);
} /* End Function mount_devfs_fs */
module_init(init_devfs_fs)
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