diff options
| -rw-r--r-- | fs/dcache.c | 64 |
1 files changed, 31 insertions, 33 deletions
diff --git a/fs/dcache.c b/fs/dcache.c index 38b1b0989a16..b9caf47d5389 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -100,30 +100,21 @@ static struct kmem_cache *dentry_cache __read_mostly; */ static inline void read_seqbegin_or_lock(seqlock_t *lock, int *seq) { - if (!(*seq & 1)) { /* Even */ + if (!(*seq & 1)) /* Even */ *seq = read_seqbegin(lock); - rcu_read_lock(); - } else /* Odd */ + else /* Odd */ write_seqlock(lock); } -/** - * read_seqretry_or_unlock - end a seqretry or lock block & return retry status - * lock : sequence lock - * seq : sequence number - * Return: 1 to retry operation again, 0 to continue - */ -static inline int read_seqretry_or_unlock(seqlock_t *lock, int *seq) +static inline int need_seqretry(seqlock_t *lock, int seq) { - if (!(*seq & 1)) { /* Even */ - rcu_read_unlock(); - if (read_seqretry(lock, *seq)) { - (*seq)++; /* Take writer lock */ - return 1; - } - } else /* Odd */ + return !(seq & 1) && read_seqretry(lock, seq); +} + +static inline void done_seqretry(seqlock_t *lock, int seq) +{ + if (seq & 1) write_sequnlock(lock); - return 0; } /* @@ -1047,7 +1038,7 @@ void shrink_dcache_for_umount(struct super_block *sb) * the parenthood after dropping the lock and check * that the sequence number still matches. */ -static struct dentry *try_to_ascend(struct dentry *old, int locked, unsigned seq) +static struct dentry *try_to_ascend(struct dentry *old, unsigned seq) { struct dentry *new = old->d_parent; @@ -1061,7 +1052,7 @@ static struct dentry *try_to_ascend(struct dentry *old, int locked, unsigned seq */ if (new != old->d_parent || (old->d_flags & DCACHE_DENTRY_KILLED) || - (!locked && read_seqretry(&rename_lock, seq))) { + need_seqretry(&rename_lock, seq)) { spin_unlock(&new->d_lock); new = NULL; } @@ -1098,13 +1089,12 @@ static void d_walk(struct dentry *parent, void *data, { struct dentry *this_parent; struct list_head *next; - unsigned seq; - int locked = 0; + unsigned seq = 0; enum d_walk_ret ret; bool retry = true; - seq = read_seqbegin(&rename_lock); again: + read_seqbegin_or_lock(&rename_lock, &seq); this_parent = parent; spin_lock(&this_parent->d_lock); @@ -1158,13 +1148,13 @@ resume: */ if (this_parent != parent) { struct dentry *child = this_parent; - this_parent = try_to_ascend(this_parent, locked, seq); + this_parent = try_to_ascend(this_parent, seq); if (!this_parent) goto rename_retry; next = child->d_u.d_child.next; goto resume; } - if (!locked && read_seqretry(&rename_lock, seq)) { + if (need_seqretry(&rename_lock, seq)) { spin_unlock(&this_parent->d_lock); goto rename_retry; } @@ -1173,17 +1163,13 @@ resume: out_unlock: spin_unlock(&this_parent->d_lock); - if (locked) - write_sequnlock(&rename_lock); + done_seqretry(&rename_lock, seq); return; rename_retry: if (!retry) return; - if (locked) - goto again; - locked = 1; - write_seqlock(&rename_lock); + seq = 1; goto again; } @@ -2745,6 +2731,7 @@ static int prepend_path(const struct path *path, char *bptr; int blen; + rcu_read_lock(); restart: bptr = *buffer; blen = *buflen; @@ -2783,8 +2770,13 @@ restart: dentry = parent; } - if (read_seqretry_or_unlock(&rename_lock, &seq)) + if (!(seq & 1)) + rcu_read_unlock(); + if (need_seqretry(&rename_lock, seq)) { + seq = 1; goto restart; + } + done_seqretry(&rename_lock, seq); if (error >= 0 && bptr == *buffer) { if (--blen < 0) @@ -2957,6 +2949,7 @@ static char *__dentry_path(struct dentry *dentry, char *buf, int buflen) int len, seq = 0; int error = 0; + rcu_read_lock(); restart: end = buf + buflen; len = buflen; @@ -2979,8 +2972,13 @@ restart: retval = end; dentry = parent; } - if (read_seqretry_or_unlock(&rename_lock, &seq)) + if (!(seq & 1)) + rcu_read_unlock(); + if (need_seqretry(&rename_lock, seq)) { + seq = 1; goto restart; + } + done_seqretry(&rename_lock, seq); if (error) goto Elong; return retval; |