linux/fs/ecryptfs
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
..
Makefile eCryptfs: remove netlink transport 2008-10-16 11:21:39 -07:00
crypto.c ecryptfs: fix memory corruption when storing crypto info in xattrs 2008-10-30 11:38:46 -07:00
debug.c eCryptfs: update comment and debug statement 2007-10-16 09:43:11 -07:00
dentry.c eCryptfs: Swap dput() and mntput() 2008-03-19 18:53:36 -07:00
ecryptfs_kernel.h CRED: Pass credentials through dentry_open() 2008-11-14 10:39:22 +11:00
file.c eCryptfs: remove retry loop in ecryptfs_readdir() 2008-10-16 11:21:38 -07:00
inode.c eCryptfs: check readlink result was not an error before using it 2008-12-31 18:07:38 -05:00
keystore.c eCryptfs: Allocate up to two scatterlists for crypto ops on keys 2008-11-19 18:49:58 -08:00
kthread.c CRED: Pass credentials through dentry_open() 2008-11-14 10:39:22 +11:00
main.c CRED: Pass credentials through dentry_open() 2008-11-14 10:39:22 +11:00
messaging.c User namespaces: set of cleanups (v2) 2008-11-24 18:57:41 -05:00
miscdev.c User namespaces: set of cleanups (v2) 2008-11-24 18:57:41 -05:00
mmap.c fs: symlink write_begin allocation context fix 2009-01-04 13:33:20 -08:00
read_write.c eCryptfs: remove unnecessary page decrypt call 2008-06-06 11:29:09 -07:00
super.c ecryptfs: remove debug as mount option, and warn if set via modprobe 2008-02-06 10:41:12 -08:00