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gfs2: Be more careful with the quota sync generation

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The quota sync generation is only ever updated under sd_quota_sync_mutex
by gfs2_quota_sync(), but its current value is fetched ouside of that
mutex, so use WRITE_ONCE() and READ_ONCE() when accessing it without
holding that mutex.

Pass the current sync generation to do_sync() from its callers to ensure
that we're not recording the wrong generation when the syncing is
done.  Also, make sure that qd->qd_sync_gen only ever moves forward.

In gfs2_quota_sync(), only write the new sync generation when we know
that there are changes.  This eliminates the need for function
sd_changed(), which we will remove in the next commit.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
This commit is contained in:
Andreas Gruenbacher 2024-06-07 15:54:21 +02:00
parent 8d89e068de
commit d9a75a6069
1 changed files with 19 additions and 8 deletions
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27
fs/gfs2/quota.c
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@ -891,7 +891,8 @@ static int gfs2_adjust_quota(struct gfs2_sbd *sdp, loff_t loc,
return err;
}
static int do_sync(unsigned int num_qd, struct gfs2_quota_data **qda)
static int do_sync(unsigned int num_qd, struct gfs2_quota_data **qda,
u64 sync_gen)
{
struct gfs2_sbd *sdp = (*qda)->qd_sbd;
struct gfs2_inode *ip = GFS2_I(sdp->sd_quota_inode);
@ -982,8 +983,13 @@ static int do_sync(unsigned int num_qd, struct gfs2_quota_data **qda)
gfs2_log_flush(ip->i_gl->gl_name.ln_sbd, ip->i_gl,
GFS2_LOG_HEAD_FLUSH_NORMAL | GFS2_LFC_DO_SYNC);
if (!error) {
for (x = 0; x < num_qd; x++)
qda[x]->qd_sync_gen = sdp->sd_quota_sync_gen;
for (x = 0; x < num_qd; x++) {
qd = qda[x];
spin_lock(&qd->qd_lockref.lock);
if (qd->qd_sync_gen < sync_gen)
qd->qd_sync_gen = sync_gen;
spin_unlock(&qd->qd_lockref.lock);
}
}
return error;
}
@ -1177,7 +1183,9 @@ void gfs2_quota_unlock(struct gfs2_inode *ip)
}
if (count) {
do_sync(count, qda);
u64 sync_gen = READ_ONCE(sdp->sd_quota_sync_gen);
do_sync(count, qda, sync_gen);
for (x = 0; x < count; x++)
qd_unlock(qda[x]);
}
@ -1323,6 +1331,7 @@ int gfs2_quota_sync(struct super_block *sb, int type)
struct gfs2_sbd *sdp = sb->s_fs_info;
struct gfs2_quota_data **qda;
unsigned int max_qd = PAGE_SIZE / sizeof(struct gfs2_holder);
u64 sync_gen;
int error = 0;
if (sb_rdonly(sdp->sd_vfs))
@ -1335,7 +1344,7 @@ int gfs2_quota_sync(struct super_block *sb, int type)
return -ENOMEM;
mutex_lock(&sdp->sd_quota_sync_mutex);
sdp->sd_quota_sync_gen++;
sync_gen = sdp->sd_quota_sync_gen + 1;
do {
struct gfs2_quota_data *iter;
@ -1344,7 +1353,7 @@ int gfs2_quota_sync(struct super_block *sb, int type)
spin_lock(&qd_lock);
list_for_each_entry(iter, &sdp->sd_quota_list, qd_list) {
if (qd_grab_sync(sdp, iter, sdp->sd_quota_sync_gen)) {
if (qd_grab_sync(sdp, iter, sync_gen)) {
qda[num_qd++] = iter;
if (num_qd == max_qd)
break;
@ -1365,8 +1374,10 @@ int gfs2_quota_sync(struct super_block *sb, int type)
break;
}
if (!error)
error = do_sync(num_qd, qda);
if (!error) {
WRITE_ONCE(sdp->sd_quota_sync_gen, sync_gen);
error = do_sync(num_qd, qda, sync_gen);
}
for (x = 0; x < num_qd; x++)
qd_unlock(qda[x]);