linux/fs/ext4
Nick Piggin 54566b2c15 fs: symlink write_begin allocation context fix
With the write_begin/write_end aops, page_symlink was broken because it
could no longer pass a GFP_NOFS type mask into the point where the
allocations happened.  They are done in write_begin, which would always
assume that the filesystem can be entered from reclaim.  This bug could
cause filesystem deadlocks.

The funny thing with having a gfp_t mask there is that it doesn't really
allow the caller to arbitrarily tinker with the context in which it can be
called.  It couldn't ever be GFP_ATOMIC, for example, because it needs to
take the page lock.  The only thing any callers care about is __GFP_FS
anyway, so turn that into a single flag.

Add a new flag for write_begin, AOP_FLAG_NOFS.  Filesystems can now act on
this flag in their write_begin function.  Change __grab_cache_page to
accept a nofs argument as well, to honour that flag (while we're there,
change the name to grab_cache_page_write_begin which is more instructive
and does away with random leading underscores).

This is really a more flexible way to go in the end anyway -- if a
filesystem happens to want any extra allocations aside from the pagecache
ones in ints write_begin function, it may now use GFP_KERNEL (rather than
GFP_NOFS) for common case allocations (eg.  ocfs2_alloc_write_ctxt, for a
random example).

[kosaki.motohiro@jp.fujitsu.com: fix ubifs]
[kosaki.motohiro@jp.fujitsu.com: fix fuse]
Signed-off-by: Nick Piggin <npiggin@suse.de>
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: <stable@kernel.org>		[2.6.28.x]
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
[ Cleaned up the calling convention: just pass in the AOP flags
  untouched to the grab_cache_page_write_begin() function.  That
  just simplifies everybody, and may even allow future expansion of the
  logic.   - Linus ]
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-01-04 13:33:20 -08:00
..
Kconfig fs/Kconfig: move ext2, ext3, ext4, JBD, JBD2 out 2008-10-20 11:43:59 -07:00
Makefile ext4: Rename ext4dev to ext4 2008-10-10 20:02:48 -04:00
acl.c
acl.h ext4: Rename ext4dev to ext4 2008-10-10 20:02:48 -04:00
balloc.c Merge branch 'next' into for-linus 2008-12-25 11:40:09 +11:00
bitmap.c
dir.c ext4: Fix duplicate entries returned from getdents() system call 2008-10-25 22:37:55 -04:00
ext4.h merge ext4_claim_free_blocks & ext4_has_free_blocks 2008-10-28 00:08:12 -04:00
ext4_extents.h Hook ext4 to the vfs fiemap interface. 2008-10-07 00:46:36 -04:00
ext4_i.h ext4: Rename ext4dev to ext4 2008-10-10 20:02:48 -04:00
ext4_jbd2.c
ext4_jbd2.h
ext4_sb.h fs: introduce bgl_lock_ptr() 2009-01-04 13:33:20 -08:00
extents.c Hook ext4 to the vfs fiemap interface. 2008-10-07 00:46:36 -04:00
file.c ext4: Rename ext4dev to ext4 2008-10-10 20:02:48 -04:00
fsync.c ext4: Add debugging markers that can be used by systemtap 2008-10-05 20:50:06 -04:00
group.h
hash.c
ialloc.c nfsd race fixes: ext4 2008-12-31 18:07:44 -05:00
inode.c fs: symlink write_begin allocation context fix 2009-01-04 13:33:20 -08:00
ioctl.c ext4: add checks for errors from jbd2 2008-10-10 20:29:21 -04:00
mballoc.c ext4: fix missing ext4_unlock_group in error path 2008-11-04 09:10:50 -05:00
mballoc.h ext4: Replace hackish ext4_mb_poll_new_transaction with commit callback 2008-10-16 20:00:24 -04:00
migrate.c
namei.c fs: symlink write_begin allocation context fix 2009-01-04 13:33:20 -08:00
namei.h
resize.c ext4: Remove old legacy block allocator 2008-10-10 09:40:52 -04:00
super.c Get rid of CONFIG_LSF 2008-12-29 08:29:51 +01:00
symlink.c ext4: Rename ext4dev to ext4 2008-10-10 20:02:48 -04:00
xattr.c ext4: Rename ext4dev to ext4 2008-10-10 20:02:48 -04:00
xattr.h ext4: Rename ext4dev to ext4 2008-10-10 20:02:48 -04:00
xattr_security.c
xattr_trusted.c
xattr_user.c