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xfs: wire up Q_XGETNEXTQUOTA / get_nextdqblk

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Add code to allow the Q_XGETNEXTQUOTA quotactl to quickly find
all active quotas by examining the quota inode, and skipping
over unallocated or uninitialized regions.

Userspace can then use this interface rather than i.e. a
getpwent() loop when asked to report all active quotas.

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
This commit is contained in:
Eric Sandeen
2016-02-08 11:27:38 +11:00
committed by Dave Chinner
parent 8aa7d37ebf
commit 296c24e26e
5 changed files with 142 additions and 9 deletions
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96
fs/xfs/xfs_dquot.c
View File

@@ -685,6 +685,56 @@ error0:
return error;
}
/*
* Advance to the next id in the current chunk, or if at the
* end of the chunk, skip ahead to first id in next allocated chunk
* using the SEEK_DATA interface.
*/
int
xfs_dq_get_next_id(
xfs_mount_t *mp,
uint type,
xfs_dqid_t *id,
loff_t eof)
{
struct xfs_inode *quotip;
xfs_fsblock_t start;
loff_t offset;
uint lock;
xfs_dqid_t next_id;
int error = 0;
/* Simple advance */
next_id = *id + 1;
/* If new ID is within the current chunk, advancing it sufficed */
if (next_id % mp->m_quotainfo->qi_dqperchunk) {
*id = next_id;
return 0;
}
/* Nope, next_id is now past the current chunk, so find the next one */
start = (xfs_fsblock_t)next_id / mp->m_quotainfo->qi_dqperchunk;
quotip = xfs_quota_inode(mp, type);
lock = xfs_ilock_data_map_shared(quotip);
offset = __xfs_seek_hole_data(VFS_I(quotip), XFS_FSB_TO_B(mp, start),
eof, SEEK_DATA);
if (offset < 0)
error = offset;
xfs_iunlock(quotip, lock);
/* -ENXIO is essentially "no more data" */
if (error)
return (error == -ENXIO ? -ENOENT: error);
/* Convert next data offset back to a quota id */
*id = XFS_B_TO_FSB(mp, offset) * mp->m_quotainfo->qi_dqperchunk;
return 0;
}
/*
* Given the file system, inode OR id, and type (UDQUOT/GDQUOT), return a
* a locked dquot, doing an allocation (if requested) as needed.
@@ -705,6 +755,7 @@ xfs_qm_dqget(
struct xfs_quotainfo *qi = mp->m_quotainfo;
struct radix_tree_root *tree = xfs_dquot_tree(qi, type);
struct xfs_dquot *dqp;
loff_t eof = 0;
int error;
ASSERT(XFS_IS_QUOTA_RUNNING(mp));
@@ -732,6 +783,21 @@ xfs_qm_dqget(
}
#endif
/* Get the end of the quota file if we need it */
if (flags & XFS_QMOPT_DQNEXT) {
struct xfs_inode *quotip;
xfs_fileoff_t last;
uint lock_mode;
quotip = xfs_quota_inode(mp, type);
lock_mode = xfs_ilock_data_map_shared(quotip);
error = xfs_bmap_last_offset(quotip, &last, XFS_DATA_FORK);
xfs_iunlock(quotip, lock_mode);
if (error)
return error;
eof = XFS_FSB_TO_B(mp, last);
}
restart:
mutex_lock(&qi->qi_tree_lock);
dqp = radix_tree_lookup(tree, id);
@@ -745,6 +811,18 @@ restart:
goto restart;
}
/* uninit / unused quota found in radix tree, keep looking */
if (flags & XFS_QMOPT_DQNEXT) {
if (XFS_IS_DQUOT_UNINITIALIZED(dqp)) {
xfs_dqunlock(dqp);
mutex_unlock(&qi->qi_tree_lock);
error = xfs_dq_get_next_id(mp, type, &id, eof);
if (error)
return error;
goto restart;
}
}
dqp->q_nrefs++;
mutex_unlock(&qi->qi_tree_lock);
@@ -771,6 +849,13 @@ restart:
if (ip)
xfs_ilock(ip, XFS_ILOCK_EXCL);
/* If we are asked to find next active id, keep looking */
if (error == -ENOENT && (flags & XFS_QMOPT_DQNEXT)) {
error = xfs_dq_get_next_id(mp, type, &id, eof);
if (!error)
goto restart;
}
if (error)
return error;
@@ -821,6 +906,17 @@ restart:
qi->qi_dquots++;
mutex_unlock(&qi->qi_tree_lock);
/* If we are asked to find next active id, keep looking */
if (flags & XFS_QMOPT_DQNEXT) {
if (XFS_IS_DQUOT_UNINITIALIZED(dqp)) {
xfs_qm_dqput(dqp);
error = xfs_dq_get_next_id(mp, type, &id, eof);
if (error)
return error;
goto restart;
}
}
dqret:
ASSERT((ip == NULL) || xfs_isilocked(ip, XFS_ILOCK_EXCL));
trace_xfs_dqget_miss(dqp);