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| author | Miklos Szeredi <miklos@szeredi.hu> | 2006-10-17 00:10:07 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@g5.osdl.org> | 2006-10-17 08:18:45 -0700 |
| commit | 7762f5a0b709b415fda132258ad37b9f2a1db994 (patch) | |
| tree | 7eb1b54dc392f2100bf2cf1e407a2480a4680e7d /include/linux/fs.h | |
| parent | 9ffbb9162312fd8113037cb3d94f787f06bbfa9a (diff) | |
| download | lwn-7762f5a0b709b415fda132258ad37b9f2a1db994.tar.gz lwn-7762f5a0b709b415fda132258ad37b9f2a1db994.zip | |
[PATCH] document i_size_write locking rules
Unless someone reads the documentation for write_seqcount_{begin,end} it is
not obvious, that i_size_write() needs locking. Especially, that lack of such
locking can result in a system hang.
Signed-off-by: Miklos Szeredi <miklos@szeredi.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'include/linux/fs.h')
| -rw-r--r-- | include/linux/fs.h | 6 |
1 files changed, 5 insertions, 1 deletions
diff --git a/include/linux/fs.h b/include/linux/fs.h index 34406ed467c3..661c7c572149 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -656,7 +656,11 @@ static inline loff_t i_size_read(struct inode *inode) #endif } - +/* + * NOTE: unlike i_size_read(), i_size_write() does need locking around it + * (normally i_mutex), otherwise on 32bit/SMP an update of i_size_seqcount + * can be lost, resulting in subsequent i_size_read() calls spinning forever. + */ static inline void i_size_write(struct inode *inode, loff_t i_size) { #if BITS_PER_LONG==32 && defined(CONFIG_SMP) |