diff options
| -rw-r--r-- | fs/dcache.c | 31 |
1 files changed, 16 insertions, 15 deletions
diff --git a/fs/dcache.c b/fs/dcache.c index 4d9df3c940e6..f3dcc6351a16 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -90,8 +90,8 @@ static struct kmem_cache *dentry_cache __read_mostly; /** * read_seqbegin_or_lock - begin a sequence number check or locking block - * lock: sequence lock - * seq : sequence number to be checked + * @lock: sequence lock + * @seq : sequence number to be checked * * First try it once optimistically without taking the lock. If that fails, * take the lock. The sequence number is also used as a marker for deciding @@ -103,7 +103,7 @@ static inline void read_seqbegin_or_lock(seqlock_t *lock, int *seq) if (!(*seq & 1)) /* Even */ *seq = read_seqbegin(lock); else /* Odd */ - write_seqlock(lock); + read_seqlock_excl(lock); } static inline int need_seqretry(seqlock_t *lock, int seq) @@ -114,7 +114,7 @@ static inline int need_seqretry(seqlock_t *lock, int seq) static inline void done_seqretry(seqlock_t *lock, int seq) { if (seq & 1) - write_sequnlock(lock); + read_sequnlock_excl(lock); } /* @@ -2673,9 +2673,9 @@ static int prepend(char **buffer, int *buflen, const char *str, int namelen) /** * prepend_name - prepend a pathname in front of current buffer pointer - * buffer: buffer pointer - * buflen: allocated length of the buffer - * name: name string and length qstr structure + * @buffer: buffer pointer + * @buflen: allocated length of the buffer + * @name: name string and length qstr structure * * With RCU path tracing, it may race with d_move(). Use ACCESS_ONCE() to * make sure that either the old or the new name pointer and length are @@ -2713,14 +2713,15 @@ static int prepend_name(char **buffer, int *buflen, struct qstr *name) * @buffer: pointer to the end of the buffer * @buflen: pointer to buffer length * - * The function tries to write out the pathname without taking any lock other - * than the RCU read lock to make sure that dentries won't go away. It only - * checks the sequence number of the global rename_lock as any change in the - * dentry's d_seq will be preceded by changes in the rename_lock sequence - * number. If the sequence number had been change, it will restart the whole - * pathname back-tracing sequence again. It performs a total of 3 trials of - * lockless back-tracing sequences before falling back to take the - * rename_lock. + * The function will first try to write out the pathname without taking any + * lock other than the RCU read lock to make sure that dentries won't go away. + * It only checks the sequence number of the global rename_lock as any change + * in the dentry's d_seq will be preceded by changes in the rename_lock + * sequence number. If the sequence number had been changed, it will restart + * the whole pathname back-tracing sequence again by taking the rename_lock. + * In this case, there is no need to take the RCU read lock as the recursive + * parent pointer references will keep the dentry chain alive as long as no + * rename operation is performed. */ static int prepend_path(const struct path *path, const struct path *root, |