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| author |   Nick Piggin <npiggin@suse.de> | 2009-01-04 12:00:53 -0800 |
|---|---|---|
| committer |   Linus Torvalds <torvalds@linux-foundation.org> | 2009-01-04 13:33:20 -0800 |
| commit | 54566b2c1594c2326a645a3551f9d989f7ba3c5e (patch) | |
| tree | b373f3283fe5e197d0df29cd6b645c35adf1076c /fs/ext3/namei.c | |
| parent | viafb: fix crashes due to 4k stack overflow (diff) | |
| download | linux-dev-54566b2c1594c2326a645a3551f9d989f7ba3c5e.tar.xz linux-dev-54566b2c1594c2326a645a3551f9d989f7ba3c5e.zip | |
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>
Diffstat (limited to 'fs/ext3/namei.c')
| -rw-r--r-- | fs/ext3/namei.c | 3 |
1 files changed, 1 insertions, 2 deletions
diff --git a/fs/ext3/namei.c b/fs/ext3/namei.c index 297ea8dfac7c..1dd2abe6313e 100644 --- a/fs/ext3/namei.c +++ b/fs/ext3/namei.c @@ -2175,8 +2175,7 @@ retry: * We have a transaction open. All is sweetness. It also sets * i_size in generic_commit_write(). */ - err = __page_symlink(inode, symname, l, - mapping_gfp_mask(inode->i_mapping) & ~__GFP_FS); + err = __page_symlink(inode, symname, l, 1); if (err) { drop_nlink(inode); unlock_new_inode(inode); |