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bcachefs: fix seqmutex_relock()

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We were grabbing the sequence number before unlock incremented it - fix
this by moving the increment to seqmutex_lock() (so the seqmutex_relock()
failure path skips the mutex_trylock()), and returning the sequence
number from unlock(), to make the API simpler and safer.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
This commit is contained in:
Kent Overstreet 2024-06-22 20:52:39 -04:00
parent 9bd01500e4
commit f44cc269a1
2 changed files with 6 additions and 13 deletions
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8
fs/bcachefs/debug.c
View File

@ -575,7 +575,6 @@ static ssize_t bch2_btree_transactions_read(struct file *file, char __user *buf,
struct bch_fs *c = i->c;
struct btree_trans *trans;
ssize_t ret = 0;
u32 seq;
i->ubuf = buf;
i->size = size;
@ -589,8 +588,7 @@ restart:
continue;
closure_get(&trans->ref);
seq = seqmutex_seq(&c->btree_trans_lock);
seqmutex_unlock(&c->btree_trans_lock);
u32 seq = seqmutex_unlock(&c->btree_trans_lock);
ret = flush_buf(i);
if (ret) {
@ -811,7 +809,6 @@ static ssize_t bch2_btree_deadlock_read(struct file *file, char __user *buf,
struct bch_fs *c = i->c;
struct btree_trans *trans;
ssize_t ret = 0;
u32 seq;
i->ubuf = buf;
i->size = size;
@ -828,8 +825,7 @@ restart:
continue;
closure_get(&trans->ref);
seq = seqmutex_seq(&c->btree_trans_lock);
seqmutex_unlock(&c->btree_trans_lock);
u32 seq = seqmutex_unlock(&c->btree_trans_lock);
ret = flush_buf(i);
if (ret) {

11
fs/bcachefs/seqmutex.h
View File

@ -19,17 +19,14 @@ static inline bool seqmutex_trylock(struct seqmutex *lock)
static inline void seqmutex_lock(struct seqmutex *lock)
{
mutex_lock(&lock->lock);
}
static inline void seqmutex_unlock(struct seqmutex *lock)
{
lock->seq++;
mutex_unlock(&lock->lock);
}
static inline u32 seqmutex_seq(struct seqmutex *lock)
static inline u32 seqmutex_unlock(struct seqmutex *lock)
{
return lock->seq;
u32 seq = lock->seq;
mutex_unlock(&lock->lock);
return seq;
}
static inline bool seqmutex_relock(struct seqmutex *lock, u32 seq)