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dea3667bc3
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Linus Torvalds dea3667bc3 vfs: get rid of insane dentry hashing rules 
The dentry hashing rules have been really quite complicated for a long
while, in odd ways.  That made functions like __d_drop() very fragile
and non-obvious.

In particular, whether a dentry was hashed or not was indicated with an
explicit DCACHE_UNHASHED bit.  That's despite the fact that the hash
abstraction that the dentries use actually have a 'is this entry hashed
or not' model (which is a simple test of the 'pprev' pointer).

The reason that was done is because we used the normal 'is this entry
unhashed' model to mark whether the dentry had _ever_ been hashed in the
dentry hash tables, and that logic goes back many years (commit
b3423415fbc2: "dcache: avoid RCU for never-hashed dentries").

That, in turn, meant that __d_drop had totally different unhashing logic
for the dentry hash table case and for the anonymous dcache case,
because in order to use the "is this dentry hashed" logic as a flag for
whether it had ever been on the RCU hash table, we had to unhash such a
dentry differently so that we'd never think that it wasn't 'unhashed'
and wouldn't be free'd correctly.

That's just insane.  It made the logic really hard to follow, when there
were two different kinds of "unhashed" states, and one of them (the one
that used "list_bl_unhashed()") really had nothing at all to do with
being unhashed per se, but with a very subtle lifetime rule instead.

So turn all of it around, and make it logical.

Instead of having a DENTRY_UNHASHED bit in d_flags to indicate whether
the dentry is on the hash chains or not, use the hash chain unhashed
logic for that.  Suddenly "d_unhashed()" just uses "list_bl_unhashed()",
and everything makes sense.

And for the lifetime rule, just use an explicit DENTRY_RCUACCEES bit.
If we ever insert the dentry into the dentry hash table so that it is
visible to RCU lookup, we mark it DENTRY_RCUACCESS to show that it now
needs the RCU lifetime rules.  Now suddently that test at dentry free
time makes sense too.

And because unhashing now is sane and doesn't depend on where the dentry
got unhashed from (because the dentry hash chain details doesn't have
some subtle side effects), we can re-unify the __d_drop() logic and use
common code for the unhashing.

Also fix one more open-coded hash chain bit_spin_lock() that I missed in
the previous chain locking cleanup commit.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-04-24 07:58:46 -07:00
..
9p fs/9p: Fix error reported by coccicheck 2011-04-15 15:26:14 -05:00
adfs Fix common misspellings 2011-03-31 11:26:23 -03:00
affs Merge branch 'for-2.6.39/core' of git://git.kernel.dk/linux-2.6-block 2011-03-24 10:16:26 -07:00
afs Fix common misspellings 2011-03-31 11:26:23 -03:00
autofs4 Fix common misspellings 2011-03-31 11:26:23 -03:00
befs Fix common misspellings 2011-03-31 11:26:23 -03:00
bfs Merge branch 'for-2.6.39/core' of git://git.kernel.dk/linux-2.6-block 2011-03-24 10:16:26 -07:00
btrfs Merge git://git.kernel.org/pub/scm/linux/kernel/git/mason/btrfs-unstable 2011-04-18 12:24:05 -07:00
cachefiles Fix common misspellings 2011-03-31 11:26:23 -03:00
ceph Merge branch 'for-linus2' of git://git.profusion.mobi/users/lucas/linux-2.6 2011-04-07 11:14:49 -07:00
cifs cifs: don't allow mmap'ed pages to be dirtied while under writeback (try #3) 2011-04-12 14:19:55 +00:00
coda codafs: fix build break when CONFIG_PROC_SYSCTL=n 2011-03-25 17:45:16 -07:00
configfs Fix common misspellings 2011-03-31 11:26:23 -03:00
cramfs cramfs: generate unique inode number for better inode cache usage 2011-01-13 08:03:23 -08:00
debugfs debugfs: Fix filesystem reference counting on debugfs_remove() failure 2011-02-18 08:07:18 -08:00
devpts fs/devpts/inode.c: correctly check d_alloc_name() return code in devpts_pty_new() 2011-03-22 17:44:17 -07:00
dlm Fix common misspellings 2011-03-31 11:26:23 -03:00
ecryptfs Fix common misspellings 2011-03-31 11:26:23 -03:00
efs block: remove per-queue plugging 2011-03-10 08:52:07 +01:00
exofs Fix common misspellings 2011-03-31 11:26:23 -03:00
exportfs vfs: Add open by file handle support 2011-03-15 02:21:44 -04:00
ext2 Fix common misspellings 2011-03-31 11:26:23 -03:00
ext3 Merge branch 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs-2.6 2011-04-08 07:35:17 -07:00
ext4 Merge branch 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4 2011-04-11 15:45:47 -07:00
fat Merge branch 'for-2.6.39/core' of git://git.kernel.dk/linux-2.6-block 2011-03-24 10:16:26 -07:00
freevxfs Fix common misspellings 2011-03-31 11:26:23 -03:00
fscache FS-Cache: Fix operation handling 2011-01-14 09:23:36 -08:00
fuse Fix common misspellings 2011-03-31 11:26:23 -03:00
gfs2 GFS2: filesystem hang caused by incorrect lock order 2011-04-18 15:23:50 +01:00
hfs Merge branch 'for-2.6.39/core' of git://git.kernel.dk/linux-2.6-block 2011-03-24 10:16:26 -07:00
hfsplus Merge branch 'for-2.6.39/core' of git://git.kernel.dk/linux-2.6-block 2011-03-24 10:16:26 -07:00
hostfs switch hostfs 2011-01-12 20:03:42 -05:00
hpfs Merge branch 'for-2.6.39/core' of git://git.kernel.dk/linux-2.6-block 2011-03-24 10:16:26 -07:00
hppfs fs: icache RCU free inodes 2011-01-07 17:50:26 +11:00
hugetlbfs mm: hugetlbfs: change remove_from_page_cache 2011-03-22 17:44:02 -07:00
isofs Merge branch 'for-2.6.39/core' of git://git.kernel.dk/linux-2.6-block 2011-03-24 10:16:26 -07:00
jbd Fix common misspellings 2011-03-31 11:26:23 -03:00
jbd2 Merge branch 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4 2011-04-11 15:45:47 -07:00
jffs2 Fix common misspellings 2011-03-31 11:26:23 -03:00
jfs Fix common misspellings 2011-03-31 11:26:23 -03:00
lockd NLM: Fix "kernel BUG at fs/lockd/host.c:417!" or ".../host.c:283!" 2011-01-25 15:24:47 -05:00
logfs Fix common misspellings 2011-03-31 11:26:23 -03:00
minix Merge branch 'for-2.6.39/core' of git://git.kernel.dk/linux-2.6-block 2011-03-24 10:16:26 -07:00
ncpfs Fix common misspellings 2011-03-31 11:26:23 -03:00
nfs nfs: don't call __mark_inode_dirty while holding i_lock 2011-04-12 14:17:24 -07:00
nfs_common Fix common misspellings 2011-03-31 11:26:23 -03:00
nfsd Open with O_CREAT flag set fails to open existing files on non writable directories 2011-04-20 11:03:01 -04:00
nilfs2 fs: export empty_aops 2011-04-05 23:51:48 +02:00
nls
notify Merge branch 'for-linus2' of git://git.profusion.mobi/users/lucas/linux-2.6 2011-04-07 11:14:49 -07:00
ntfs Fix common misspellings 2011-03-31 11:26:23 -03:00
ocfs2 Fix common misspellings 2011-03-31 11:26:23 -03:00
omfs Merge branch 'for-2.6.39/core' of git://git.kernel.dk/linux-2.6-block 2011-03-24 10:16:26 -07:00
openpromfs fs: icache RCU free inodes 2011-01-07 17:50:26 +11:00
partitions fs/partitions/ldm.c: fix oops caused by corrupted partition table 2011-04-14 16:06:54 -07:00
proc proc: do proper range check on readdir offset 2011-04-18 10:36:54 -07:00
pstore Fix common misspellings 2011-03-31 11:26:23 -03:00
qnx4 block: remove per-queue plugging 2011-03-10 08:52:07 +01:00
quota Merge branch 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs-2.6 2011-04-08 07:35:17 -07:00
ramfs ramfs: fix memleak on no-mmu arch 2011-04-14 16:06:56 -07:00
reiserfs Fix common misspellings 2011-03-31 11:26:23 -03:00
romfs fs: icache RCU free inodes 2011-01-07 17:50:26 +11:00
squashfs Fix common misspellings 2011-03-31 11:26:23 -03:00
sysfs kconfig: rename CONFIG_EMBEDDED to CONFIG_EXPERT 2011-01-20 17:02:05 -08:00
sysv Merge branch 'for-2.6.39/core' of git://git.kernel.dk/linux-2.6-block 2011-03-24 10:16:26 -07:00
ubifs UBIFS: fix compilation warnings when compiling with gcc 4.5 2011-04-13 11:59:09 +03:00
udf Merge branch 'for-2.6.39/core' of git://git.kernel.dk/linux-2.6-block 2011-03-24 10:16:26 -07:00
ufs Merge branch 'for-linus2' of git://git.profusion.mobi/users/lucas/linux-2.6 2011-04-07 11:14:49 -07:00
xfs xfs: fix duplicate message output 2011-04-20 11:36:49 -05:00
aio.c Merge branch 'for-2.6.39/core' of git://git.kernel.dk/linux-2.6-block 2011-03-24 10:16:26 -07:00
anon_inodes.c sanitize vfsmount refcounting changes 2011-01-16 13:47:07 -05:00
attr.c Fix common misspellings 2011-03-31 11:26:23 -03:00
bad_inode.c fs: provide rcu-walk aware permission i_ops 2011-01-07 17:50:29 +11:00
binfmt_aout.c
binfmt_elf_fdpic.c
binfmt_elf.c brk: COMPAT_BRK: fix detection of randomized brk 2011-04-14 16:06:55 -07:00
binfmt_em86.c
binfmt_flat.c Fix common misspellings 2011-03-31 11:26:23 -03:00
binfmt_misc.c convert get_sb_single() users 2010-10-29 04:16:28 -04:00
binfmt_script.c
binfmt_som.c
bio-integrity.c block: Require subsystems to explicitly allocate bio_set integrity mempool 2011-03-17 11:11:05 +01:00
bio.c Fix common misspellings 2011-03-31 11:26:23 -03:00
block_dev.c Fix common misspellings 2011-03-31 11:26:23 -03:00
buffer.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6 2011-03-24 19:01:30 -07:00
char_dev.c Merge branch 'for-2.6.38/core' of git://git.kernel.dk/linux-2.6-block 2011-01-13 10:45:01 -08:00
compat_binfmt_elf.c
compat_ioctl.c Merge branch 'tty-next' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty-2.6 2011-01-07 14:39:20 -08:00
compat.c select: remove unused MAX_SELECT_SECONDS 2011-03-21 00:16:08 -04:00
dcache.c vfs: get rid of insane dentry hashing rules 2011-04-24 07:58:46 -07:00
dcookies.c
direct-io.c Merge branch 'for-2.6.39/core' of git://git.kernel.dk/linux-2.6-block 2011-03-24 10:16:26 -07:00
drop_caches.c fs: move i_sb_list out from under inode_lock 2011-03-24 21:16:32 -04:00
eventfd.c Docbook: add fs/eventfd.c and fix typos in it 2011-02-21 15:07:04 -08:00
eventpoll.c Fix common misspellings 2011-03-31 11:26:23 -03:00
exec.c Small typo fix... 2011-03-21 00:16:09 -04:00
fcntl.c userns: rename is_owner_or_cap to inode_owner_or_capable 2011-03-23 19:47:13 -07:00
fhandle.c fs/fhandle.c: add <linux/personality.h> for ia64 2011-04-14 16:06:56 -07:00
fifo.c Filesystem: fifo: Fixed coding style issue. 2011-03-21 00:16:09 -04:00
file_table.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6 2011-03-16 13:26:17 -07:00
file.c
filesystems.c fs: synchronize_rcu when unregister_filesystem success not failure 2011-04-17 10:42:01 -07:00
fs_struct.c sanitize vfsmount refcounting changes 2011-01-16 13:47:07 -05:00
fs-writeback.c Fix common misspellings 2011-03-31 11:26:23 -03:00
generic_acl.c userns: rename is_owner_or_cap to inode_owner_or_capable 2011-03-23 19:47:13 -07:00
inode.c fs: export empty_aops 2011-04-05 23:51:48 +02:00
internal.h fs: move i_wb_list out from under inode_lock 2011-03-24 21:17:51 -04:00
ioctl.c vfs: cleanup do_vfs_ioctl() 2011-03-21 00:16:08 -04:00
ioprio.c ioprio: grab rcu_read_lock in sys_ioprio_{set,get}() 2010-11-15 10:23:31 +01:00
Kconfig Merge branch 'release' of git://git.kernel.org/pub/scm/linux/kernel/git/aegl/linux-2.6 2011-03-16 19:01:29 -07:00
Kconfig.binfmt
libfs.c pass default dentry_operations to mount_pseudo() 2011-01-12 20:03:43 -05:00
locks.c Merge branch 'for-2.6.39' of git://linux-nfs.org/~bfields/linux 2011-03-24 08:20:39 -07:00
Makefile Merge branch 'release' of git://git.kernel.org/pub/scm/linux/kernel/git/aegl/linux-2.6 2011-03-16 19:01:29 -07:00
mbcache.c Fix common misspellings 2011-03-31 11:26:23 -03:00
mpage.c fs: make mpage read/write_pages() plug 2011-03-10 08:52:26 +01:00
namei.c vfs: Fix absolute RCU path walk failures due to uninitialized seq number 2011-04-15 15:28:12 -07:00
namespace.c Revert "vfs: Export file system uuid via /proc/<pid>/mountinfo" 2011-04-12 13:35:56 -07:00
nfsctl.c open-style analog of vfs_path_lookup() 2011-03-14 09:15:28 -04:00
no-block.c
open.c fs: Use BUG_ON(!mnt) at dentry_open(). 2011-03-21 01:10:41 -04:00
pipe.c Fix broken "pipe: use event aware wakeups" optimization 2011-01-20 16:21:59 -08:00
pnode.c fs: scale mntget/mntput 2011-01-07 17:50:33 +11:00
pnode.h
posix_acl.c NFS: Prevent memory allocation failure in nfsacl_encode() 2011-01-25 15:24:47 -05:00
read_write.c fix signedness mess in rw_verify_area() on 64bit architectures 2011-01-12 20:06:58 -05:00
read_write.h
readdir.c
select.c select: remove unused MAX_SELECT_SECONDS 2011-03-21 00:16:08 -04:00
seq_file.c
signalfd.c
splice.c Merge branch 'for-2.6.38/core' of git://git.kernel.dk/linux-2.6-block 2011-01-13 10:45:01 -08:00
stack.c
stat.c readlinkat(), fchownat() and fstatat() with empty relative pathnames 2011-03-15 02:21:45 -04:00
statfs.c clean statfs-like syscalls up 2011-03-14 09:15:28 -04:00
super.c Merge branch 'for-2.6.39/core' of git://git.kernel.dk/linux-2.6-block 2011-03-24 10:16:26 -07:00
sync.c Merge branch 'for-2.6.39/core' of git://git.kernel.dk/linux-2.6-block 2011-03-24 10:16:26 -07:00
timerfd.c
utimes.c userns: rename is_owner_or_cap to inode_owner_or_capable 2011-03-23 19:47:13 -07:00
xattr_acl.c
xattr.c vfs: Pass setxattr(2) flags properly 2011-04-21 07:34:44 -07:00