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gfs2: use i_lock spin_lock for inode qadata

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Before this patch, functions gfs2_qa_get and _put used the i_rw_mutex to
prevent simultaneous access to its i_qadata. But i_rw_mutex is now used
for many other things, including iomap_begin and end, which causes a
conflict according to lockdep. We cannot just remove the lock since
simultaneous opens (gfs2_open -> gfs2_open_common -> gfs2_qa_get) can
then stomp on each others values for i_qadata.

This patch solves the conflict by using the i_lock spin_lock in the inode
to prevent simultaneous access.

Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
This commit is contained in:
Bob Peterson 2022-02-11 10:50:08 -05:00 committed by Andreas Gruenbacher
parent f4a47561fc
commit 5fcff61eea
1 changed files with 20 additions and 12 deletions
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32
fs/gfs2/quota.c
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@ -528,34 +528,42 @@ static void qdsb_put(struct gfs2_quota_data *qd)
*/
int gfs2_qa_get(struct gfs2_inode *ip)
{
int error = 0;
struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
struct inode *inode = &ip->i_inode;
if (sdp->sd_args.ar_quota == GFS2_QUOTA_OFF)
return 0;
down_write(&ip->i_rw_mutex);
spin_lock(&inode->i_lock);
if (ip->i_qadata == NULL) {
ip->i_qadata = kmem_cache_zalloc(gfs2_qadata_cachep, GFP_NOFS);
if (!ip->i_qadata) {
error = -ENOMEM;
goto out;
}
struct gfs2_qadata *tmp;
spin_unlock(&inode->i_lock);
tmp = kmem_cache_zalloc(gfs2_qadata_cachep, GFP_NOFS);
if (!tmp)
return -ENOMEM;
spin_lock(&inode->i_lock);
if (ip->i_qadata == NULL)
ip->i_qadata = tmp;
else
kmem_cache_free(gfs2_qadata_cachep, tmp);
}
ip->i_qadata->qa_ref++;
out:
up_write(&ip->i_rw_mutex);
return error;
spin_unlock(&inode->i_lock);
return 0;
}
void gfs2_qa_put(struct gfs2_inode *ip)
{
down_write(&ip->i_rw_mutex);
struct inode *inode = &ip->i_inode;
spin_lock(&inode->i_lock);
if (ip->i_qadata && --ip->i_qadata->qa_ref == 0) {
kmem_cache_free(gfs2_qadata_cachep, ip->i_qadata);
ip->i_qadata = NULL;
}
up_write(&ip->i_rw_mutex);
spin_unlock(&inode->i_lock);
}
int gfs2_quota_hold(struct gfs2_inode *ip, kuid_t uid, kgid_t gid)