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xfs: reduce ilock roundtrips in xfs_qm_vop_dqalloc

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xfs_qm_vop_dqalloc only needs the (exclusive) ilock for attaching dquots
to the inode if not done so yet.  All the other locks don't touch the inode
and don't need the ilock - the i_rwsem / iolock protects against changes
to the IDs while we are in a method, and the ilock would not help because
dropping it for the dqget calls would be racy anyway.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
This commit is contained in:
Christoph Hellwig
2025-11-10 14:23:10 +01:00
committed by Carlos Maiolino
parent 13d3c1a045
commit 6a7bb6ccd0
1 changed files with 3 additions and 29 deletions
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32
fs/xfs/xfs_qm.c
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@@ -1861,16 +1861,12 @@ xfs_qm_vop_dqalloc(
struct xfs_dquot *gq = NULL;
struct xfs_dquot *pq = NULL;
int error;
uint lockflags;
if (!XFS_IS_QUOTA_ON(mp))
return 0;
ASSERT(!xfs_is_metadir_inode(ip));
lockflags = XFS_ILOCK_EXCL;
xfs_ilock(ip, lockflags);
if ((flags & XFS_QMOPT_INHERIT) && XFS_INHERIT_GID(ip))
gid = inode->i_gid;
@@ -1879,37 +1875,22 @@ xfs_qm_vop_dqalloc(
* if necessary. The dquot(s) will not be locked.
*/
if (XFS_NOT_DQATTACHED(mp, ip)) {
xfs_ilock(ip, XFS_ILOCK_EXCL);
error = xfs_qm_dqattach_locked(ip, true);
if (error) {
xfs_iunlock(ip, lockflags);
xfs_iunlock(ip, XFS_ILOCK_EXCL);
if (error)
return error;
}
}
if ((flags & XFS_QMOPT_UQUOTA) && XFS_IS_UQUOTA_ON(mp)) {
ASSERT(O_udqpp);
if (!uid_eq(inode->i_uid, uid)) {
/*
* What we need is the dquot that has this uid, and
* if we send the inode to dqget, the uid of the inode
* takes priority over what's sent in the uid argument.
* We must unlock inode here before calling dqget if
* we're not sending the inode, because otherwise
* we'll deadlock by doing trans_reserve while
* holding ilock.
*/
xfs_iunlock(ip, lockflags);
error = xfs_qm_dqget(mp, from_kuid(user_ns, uid),
XFS_DQTYPE_USER, true, &uq);
if (error) {
ASSERT(error != -ENOENT);
return error;
}
/*
* Get the ilock in the right order.
*/
lockflags = XFS_ILOCK_SHARED;
xfs_ilock(ip, lockflags);
} else {
/*
* Take an extra reference, because we'll return
@@ -1922,15 +1903,12 @@ xfs_qm_vop_dqalloc(
if ((flags & XFS_QMOPT_GQUOTA) && XFS_IS_GQUOTA_ON(mp)) {
ASSERT(O_gdqpp);
if (!gid_eq(inode->i_gid, gid)) {
xfs_iunlock(ip, lockflags);
error = xfs_qm_dqget(mp, from_kgid(user_ns, gid),
XFS_DQTYPE_GROUP, true, &gq);
if (error) {
ASSERT(error != -ENOENT);
goto error_rele;
}
lockflags = XFS_ILOCK_SHARED;
xfs_ilock(ip, lockflags);
} else {
ASSERT(ip->i_gdquot);
gq = xfs_qm_dqhold(ip->i_gdquot);
@@ -1939,15 +1917,12 @@ xfs_qm_vop_dqalloc(
if ((flags & XFS_QMOPT_PQUOTA) && XFS_IS_PQUOTA_ON(mp)) {
ASSERT(O_pdqpp);
if (ip->i_projid != prid) {
xfs_iunlock(ip, lockflags);
error = xfs_qm_dqget(mp, prid,
XFS_DQTYPE_PROJ, true, &pq);
if (error) {
ASSERT(error != -ENOENT);
goto error_rele;
}
lockflags = XFS_ILOCK_SHARED;
xfs_ilock(ip, lockflags);
} else {
ASSERT(ip->i_pdquot);
pq = xfs_qm_dqhold(ip->i_pdquot);
@@ -1955,7 +1930,6 @@ xfs_qm_vop_dqalloc(
}
trace_xfs_dquot_dqalloc(ip);
xfs_iunlock(ip, lockflags);
if (O_udqpp)
*O_udqpp = uq;
else