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ce8d2cdf3d
linux/fs
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Dave Hansen ce8d2cdf3d r/o bind mounts: filesystem helpers for custom 'struct file's 
Why do we need r/o bind mounts?

This feature allows a read-only view into a read-write filesystem.  In the
process of doing that, it also provides infrastructure for keeping track of
the number of writers to any given mount.

This has a number of uses.  It allows chroots to have parts of filesystems
writable.  It will be useful for containers in the future because users may
have root inside a container, but should not be allowed to write to
somefilesystems.  This also replaces patches that vserver has had out of the
tree for several years.

It allows security enhancement by making sure that parts of your filesystem
read-only (such as when you don't trust your FTP server), when you don't want
to have entire new filesystems mounted, or when you want atime selectively
updated.  I've been using the following script to test that the feature is
working as desired.  It takes a directory and makes a regular bind and a r/o
bind mount of it.  It then performs some normal filesystem operations on the
three directories, including ones that are expected to fail, like creating a
file on the r/o mount.

This patch:

Some filesystems forego the vfs and may_open() and create their own 'struct
file's.

This patch creates a couple of helper functions which can be used by these
filesystems, and will provide a unified place which the r/o bind mount code
may patch.

Also, rename an existing, static-scope init_file() to a less generic name.

Signed-off-by: Dave Hansen <haveblue@us.ibm.com>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-17 08:43:04 -07:00
..
9p 9PFS: clean up explicit check for mandatory locks 2007-10-09 18:32:46 -04:00
adfs Slab API: remove useless ctor parameter and reorder parameters 2007-10-17 08:42:45 -07:00
affs fs: mark nibblemap const 2007-10-17 08:42:47 -07:00
afs KEYS: Make request_key() and co fundamentally asynchronous 2007-10-17 08:42:57 -07:00
autofs
autofs4 fs/autofs4/inode.c: kmalloc + memset conversion to kzalloc 2007-10-17 08:42:50 -07:00
befs Slab API: remove useless ctor parameter and reorder parameters 2007-10-17 08:42:45 -07:00
bfs Slab API: remove useless ctor parameter and reorder parameters 2007-10-17 08:42:45 -07:00
cifs Slab API: remove useless ctor parameter and reorder parameters 2007-10-17 08:42:45 -07:00
coda Slab API: remove useless ctor parameter and reorder parameters 2007-10-17 08:42:45 -07:00
configfs r/o bind mounts: filesystem helpers for custom 'struct file's 2007-10-17 08:43:04 -07:00
cramfs cramfs: error message about endianess 2007-10-17 08:42:53 -07:00
debugfs docbook: fix filesystems content 2007-10-15 17:56:36 -07:00
devpts
dlm menuconfig: transform NLS and DLM menus 2007-10-17 08:43:00 -07:00
ecryptfs Clean up duplicate includes in fs/ecryptfs/ 2007-10-17 08:42:48 -07:00
efs Slab API: remove useless ctor parameter and reorder parameters 2007-10-17 08:42:45 -07:00
exportfs knfsd: exportfs: split out reconnecting a dentry from find_exported_dentry 2007-07-17 10:23:06 -07:00
ext2 ext2 reservations 2007-10-17 08:43:02 -07:00
ext3 ext3: lighten up resize transaction requirements 2007-10-17 08:43:01 -07:00
ext4 Fix f_version type: should be u64 instead of unsigned long 2007-10-17 08:42:53 -07:00
fat Slab API: remove useless ctor parameter and reorder parameters 2007-10-17 08:42:45 -07:00
freevxfs mm: Remove slab destructors from kmem_cache_create(). 2007-07-20 10:11:58 +09:00
fuse fuse: clean up execute permission checking 2007-10-17 08:43:04 -07:00
gfs2 fs: correct SuS compliance for open of large file without options 2007-10-17 08:43:01 -07:00
hfs Slab API: remove useless ctor parameter and reorder parameters 2007-10-17 08:42:45 -07:00
hfsplus Slab API: remove useless ctor parameter and reorder parameters 2007-10-17 08:42:45 -07:00
hostfs uml: fix hostfs style 2007-10-16 09:43:07 -07:00
hpfs Slab API: remove useless ctor parameter and reorder parameters 2007-10-17 08:42:45 -07:00
hppfs
hugetlbfs r/o bind mounts: filesystem helpers for custom 'struct file's 2007-10-17 08:43:04 -07:00
isofs fs/isofs/namei.c: Remove uninitialized local vars warning 2007-10-17 08:42:58 -07:00
jbd Group short-lived and reclaimable kernel allocations 2007-10-16 09:43:00 -07:00
jbd2 mm: Remove slab destructors from kmem_cache_create(). 2007-07-20 10:11:58 +09:00
jffs2 Slab API: remove useless ctor parameter and reorder parameters 2007-10-17 08:42:45 -07:00
jfs introduce I_SYNC 2007-10-17 08:43:02 -07:00
lockd NFS/SUNRPC: use transport protocol naming 2007-10-09 17:17:53 -04:00
minix limit minixfs printks on corrupted dir i_size 2007-10-17 08:42:53 -07:00
msdos
ncpfs Slab API: remove useless ctor parameter and reorder parameters 2007-10-17 08:42:45 -07:00
nfs Slab API: remove useless ctor parameter and reorder parameters 2007-10-17 08:42:45 -07:00
nfs_common
nfsd fs/nfsd/export.c: make 3 functions static 2007-10-16 09:43:10 -07:00
nls menuconfig: transform NLS and DLM menus 2007-10-17 08:43:00 -07:00
ntfs writeback: fix ntfs with sb_has_dirty_inodes() 2007-10-17 08:43:02 -07:00
ocfs2 Fix f_version type: should be u64 instead of unsigned long 2007-10-17 08:42:53 -07:00
openpromfs Slab API: remove useless ctor parameter and reorder parameters 2007-10-17 08:42:45 -07:00
partitions fs/partitions/sun.c endianness annotations 2007-10-14 12:41:51 -07:00
proc Don't truncate /proc/PID/environ at 4096 characters 2007-10-17 08:43:00 -07:00
qnx4 Slab API: remove useless ctor parameter and reorder parameters 2007-10-17 08:42:45 -07:00
ramfs Remove valueless definition of hard-selected RAMFS option 2007-10-17 08:42:56 -07:00
reiserfs reiserfs: do not repair wrong journal params 2007-10-17 08:43:01 -07:00
romfs fs/romfs/inode.c: trivial improvements 2007-10-17 08:42:47 -07:00
smbfs Slab API: remove useless ctor parameter and reorder parameters 2007-10-17 08:42:45 -07:00
sysfs spin_lock_unlocked cleanups 2007-10-17 08:43:01 -07:00
sysv Slab API: remove useless ctor parameter and reorder parameters 2007-10-17 08:42:45 -07:00
udf fs/udf/balloc.c: mark a variable as uninitialized_var() 2007-10-17 08:43:00 -07:00
ufs ufs: Fix mount check in ufs_fill_super() 2007-10-17 08:42:51 -07:00
vfat
xfs introduce I_SYNC 2007-10-17 08:43:02 -07:00
aio.c aio: account I/O wait time properly 2007-10-17 08:42:53 -07:00
anon_inodes.c anon-inodes use open coded atomic_inc for the shared inode 2007-10-17 08:43:00 -07:00
attr.c Introduce is_owner_or_cap() to wrap CAP_FOWNER use with fsuid check 2007-07-17 12:00:03 -07:00
bad_inode.c sendfile: remove bad_sendfile() from bad_file_ops 2007-07-10 08:04:15 +02:00
binfmt_aout.c core_pattern: ignore RLIMIT_CORE if core_pattern is a pipe 2007-10-17 08:42:50 -07:00
binfmt_elf_fdpic.c core_pattern: ignore RLIMIT_CORE if core_pattern is a pipe 2007-10-17 08:42:50 -07:00
binfmt_elf.c Break ELF_PLATFORM and stack pointer randomization dependency 2007-10-17 08:43:01 -07:00
binfmt_em86.c
binfmt_flat.c binfmt_flat: warning fixes 2007-10-17 08:42:54 -07:00
binfmt_misc.c mm: variable length argument support 2007-07-19 10:04:45 -07:00
binfmt_script.c mm: variable length argument support 2007-07-19 10:04:45 -07:00
binfmt_som.c core_pattern: ignore RLIMIT_CORE if core_pattern is a pipe 2007-10-17 08:42:50 -07:00
bio.c bio: make freeing of ->bi_io_vec conditional in bio_free() 2007-10-16 11:03:52 +02:00
block_dev.c Slab API: remove useless ctor parameter and reorder parameters 2007-10-17 08:42:45 -07:00
buffer.c writeback: remove pages_skipped accounting in __block_write_full_page() 2007-10-17 08:43:02 -07:00
char_dev.c mm: bdi init hooks 2007-10-17 08:42:45 -07:00
compat_ioctl.c Clean up duplicate includes in fs/ 2007-10-17 08:42:48 -07:00
compat.c mm: variable length argument support 2007-07-19 10:04:45 -07:00
dcache.c vfs: use the predefined d_unhashed inline function instead 2007-10-17 08:43:00 -07:00
dcookies.c Remove fs.h from mm.h 2007-07-29 17:09:29 -07:00
direct-io.c remove ZERO_PAGE 2007-10-16 09:42:53 -07:00
dnotify.c mm: Remove slab destructors from kmem_cache_create(). 2007-07-20 10:11:58 +09:00
dquot.c quota: send messages via netlink 2007-10-17 08:42:56 -07:00
drop_caches.c invalidate_mapping_pages(): add cond_resched 2007-07-16 09:05:36 -07:00
eventfd.c
eventpoll.c mm: Remove slab destructors from kmem_cache_create(). 2007-07-20 10:11:58 +09:00
exec.c exec: RT sub-thread can livelock and monopolize CPU on exec 2007-10-17 08:42:54 -07:00
fcntl.c F_DUPFD_CLOEXEC implementation 2007-10-17 08:43:01 -07:00
fifo.c
file_table.c r/o bind mounts: filesystem helpers for custom 'struct file's 2007-10-17 08:43:04 -07:00
file.c
filesystems.c
fs-writeback.c introduce I_SYNC 2007-10-17 08:43:02 -07:00
generic_acl.c Introduce is_owner_or_cap() to wrap CAP_FOWNER use with fsuid check 2007-07-17 12:00:03 -07:00
inode.c introduce I_SYNC 2007-10-17 08:43:02 -07:00
inotify_user.c change inotifyfs magic as the same magic is used for futexfs 2007-10-17 08:43:00 -07:00
inotify.c
internal.h
ioctl.c drop obsolete sys_ioctl export 2007-07-16 09:05:48 -07:00
ioprio.c
Kconfig menuconfig: transform Network Filesystems menu 2007-10-17 08:43:00 -07:00
Kconfig.binfmt
libfs.c make fs/libfs.c:simple_commit_write() static 2007-10-17 08:42:53 -07:00
locks.c Slab API: remove useless ctor parameter and reorder parameters 2007-10-17 08:42:45 -07:00
Makefile Remove valueless definition of hard-selected RAMFS option 2007-10-17 08:42:56 -07:00
mbcache.c mm: Remove slab destructors from kmem_cache_create(). 2007-07-20 10:11:58 +09:00
mpage.c mm: buffered write cleanup 2007-10-16 09:42:54 -07:00
namei.c fix execute checking in permission() 2007-10-17 08:42:52 -07:00
namespace.c fs: remove the unused mempages parameter 2007-10-17 08:42:49 -07:00
nfsctl.c nfsctl: use vfs_path_lookup 2007-07-19 10:04:45 -07:00
no-block.c
open.c fs: correct SuS compliance for open of large file without options 2007-10-17 08:43:01 -07:00
pipe.c sched: affine sync wakeups 2007-10-15 17:00:19 +02:00
pnode.c
pnode.h
posix_acl.c
quota_v1.c
quota_v2.c
quota.c [IA64] Fix build failure in fs/quota.c 2007-07-27 15:40:13 -07:00
read_write.c Cleanup macros for distinguishing mandatory locks 2007-10-09 18:32:46 -04:00
read_write.h
readdir.c
select.c Use ERESTART_RESTARTBLOCK if poll() is interrupted by a signal 2007-10-17 08:42:53 -07:00
seq_file.c [FS] seq_file: Introduce the seq_open_private() 2007-10-10 16:55:33 -07:00
signalfd.c rename signalfd_siginfo fields 2007-10-17 08:43:01 -07:00
splice.c Merge branch 'for-linus' of git://git.kernel.dk/data/git/linux-2.6-block 2007-10-16 10:09:16 -07:00
stack.c
stat.c
super.c writeback: fix periodic superblock dirty inode flushing 2007-10-17 08:43:02 -07:00
sync.c
timerfd.c make timerfd return a u64 and fix the __put_user 2007-07-26 11:35:17 -07:00
utimes.c VFS: check nanoseconds in utimensat 2007-10-17 08:42:52 -07:00
xattr_acl.c
xattr.c Introduce is_owner_or_cap() to wrap CAP_FOWNER use with fsuid check 2007-07-17 12:00:03 -07:00