xfs: wire up Q_XGETNEXTQUOTA / get_nextdqblk
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>
diff --git a/fs/xfs/xfs_dquot.c b/fs/xfs/xfs_dquot.c
index 5dbde0d..2f0502f 100644
--- a/fs/xfs/xfs_dquot.c
+++ b/fs/xfs/xfs_dquot.c
@@ -686,6 +686,56 @@
}
/*
+ * 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.
* When both an inode and an id are given, the inode's id takes precedence.
@@ -705,6 +755,7 @@
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 @@
}
#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 @@
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 @@
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 @@
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);