WSL2-Linux-Kernel/fs/affs
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
..
Changes Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
Makefile Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
affs.h affs: convert s_bmlock into a mutex 2008-07-26 12:00:03 -07:00
amigaffs.c iget: stop AFFS from using iget() and read_inode() 2008-02-07 08:42:27 -08:00
bitmap.c affs: convert s_bmlock into a mutex 2008-07-26 12:00:03 -07:00
dir.c [PATCH] fix ->llseek() for a bunch of directories 2008-08-25 01:18:09 -04:00
file.c fs: symlink write_begin allocation context fix 2009-01-04 13:33:20 -08:00
inode.c CRED: Wrap task credential accesses in the AFFS filesystem 2008-11-14 10:38:45 +11:00
namei.c [PATCH] fix reservation discarding in affs 2008-05-06 13:45:33 -04:00
super.c CRED: Wrap task credential accesses in the AFFS filesystem 2008-11-14 10:38:45 +11:00
symlink.c [PATCH] mark struct inode_operations const 1 2007-02-12 09:48:46 -08:00