xfs: reclaim inodes under a write lock
Make the inode tree reclaim walk exclusive to avoid races with
concurrent sync walkers and lookups. This is a version of a patch
posted by Christoph Hellwig that avoids all the code duplication.
Signed-off-by: Dave Chinner <david@fromorbit.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Alex Elder <aelder@sgi.com>
diff --git a/fs/xfs/linux-2.6/xfs_sync.c b/fs/xfs/linux-2.6/xfs_sync.c
index 6fed97a..e19d255 100644
--- a/fs/xfs/linux-2.6/xfs_sync.c
+++ b/fs/xfs/linux-2.6/xfs_sync.c
@@ -65,7 +65,6 @@
* as the tree is sparse and a gang lookup walks to find
* the number of objects requested.
*/
- read_lock(&pag->pag_ici_lock);
if (tag == XFS_ICI_NO_TAG) {
nr_found = radix_tree_gang_lookup(&pag->pag_ici_root,
(void **)&ip, *first_index, 1);
@@ -74,7 +73,7 @@
(void **)&ip, *first_index, 1, tag);
}
if (!nr_found)
- goto unlock;
+ return NULL;
/*
* Update the index for the next lookup. Catch overflows
@@ -84,13 +83,8 @@
*/
*first_index = XFS_INO_TO_AGINO(mp, ip->i_ino + 1);
if (*first_index < XFS_INO_TO_AGINO(mp, ip->i_ino))
- goto unlock;
-
+ return NULL;
return ip;
-
-unlock:
- read_unlock(&pag->pag_ici_lock);
- return NULL;
}
STATIC int
@@ -100,7 +94,8 @@
int (*execute)(struct xfs_inode *ip,
struct xfs_perag *pag, int flags),
int flags,
- int tag)
+ int tag,
+ int exclusive)
{
struct xfs_perag *pag = &mp->m_perag[ag];
uint32_t first_index;
@@ -114,10 +109,20 @@
int error = 0;
xfs_inode_t *ip;
+ if (exclusive)
+ write_lock(&pag->pag_ici_lock);
+ else
+ read_lock(&pag->pag_ici_lock);
ip = xfs_inode_ag_lookup(mp, pag, &first_index, tag);
- if (!ip)
+ if (!ip) {
+ if (exclusive)
+ write_unlock(&pag->pag_ici_lock);
+ else
+ read_unlock(&pag->pag_ici_lock);
break;
+ }
+ /* execute releases pag->pag_ici_lock */
error = execute(ip, pag, flags);
if (error == EAGAIN) {
skipped++;
@@ -125,9 +130,8 @@
}
if (error)
last_error = error;
- /*
- * bail out if the filesystem is corrupted.
- */
+
+ /* bail out if the filesystem is corrupted. */
if (error == EFSCORRUPTED)
break;
@@ -148,7 +152,8 @@
int (*execute)(struct xfs_inode *ip,
struct xfs_perag *pag, int flags),
int flags,
- int tag)
+ int tag,
+ int exclusive)
{
int error = 0;
int last_error = 0;
@@ -157,7 +162,8 @@
for (ag = 0; ag < mp->m_sb.sb_agcount; ag++) {
if (!mp->m_perag[ag].pag_ici_init)
continue;
- error = xfs_inode_ag_walk(mp, ag, execute, flags, tag);
+ error = xfs_inode_ag_walk(mp, ag, execute, flags, tag,
+ exclusive);
if (error) {
last_error = error;
if (error == EFSCORRUPTED)
@@ -181,11 +187,7 @@
return EFSCORRUPTED;
}
- /*
- * If we can't get a reference on the inode, it must be in reclaim.
- * Leave it for the reclaim code to flush. Also avoid inodes that
- * haven't been fully initialised.
- */
+ /* If we can't get a reference on the inode, it must be in reclaim. */
if (!igrab(inode)) {
read_unlock(&pag->pag_ici_lock);
return ENOENT;
@@ -282,7 +284,7 @@
ASSERT((flags & ~(SYNC_TRYLOCK|SYNC_WAIT)) == 0);
error = xfs_inode_ag_iterator(mp, xfs_sync_inode_data, flags,
- XFS_ICI_NO_TAG);
+ XFS_ICI_NO_TAG, 0);
if (error)
return XFS_ERROR(error);
@@ -304,7 +306,7 @@
ASSERT((flags & ~SYNC_WAIT) == 0);
return xfs_inode_ag_iterator(mp, xfs_sync_inode_attr, flags,
- XFS_ICI_NO_TAG);
+ XFS_ICI_NO_TAG, 0);
}
STATIC int
@@ -664,60 +666,6 @@
kthread_stop(mp->m_sync_task);
}
-STATIC int
-xfs_reclaim_inode(
- xfs_inode_t *ip,
- int sync_mode)
-{
- xfs_perag_t *pag = xfs_get_perag(ip->i_mount, ip->i_ino);
-
- /* The hash lock here protects a thread in xfs_iget_core from
- * racing with us on linking the inode back with a vnode.
- * Once we have the XFS_IRECLAIM flag set it will not touch
- * us.
- */
- write_lock(&pag->pag_ici_lock);
- spin_lock(&ip->i_flags_lock);
- if (__xfs_iflags_test(ip, XFS_IRECLAIM) ||
- !__xfs_iflags_test(ip, XFS_IRECLAIMABLE)) {
- spin_unlock(&ip->i_flags_lock);
- write_unlock(&pag->pag_ici_lock);
- return -EAGAIN;
- }
- __xfs_iflags_set(ip, XFS_IRECLAIM);
- spin_unlock(&ip->i_flags_lock);
- write_unlock(&pag->pag_ici_lock);
- xfs_put_perag(ip->i_mount, pag);
-
- /*
- * If the inode is still dirty, then flush it out. If the inode
- * is not in the AIL, then it will be OK to flush it delwri as
- * long as xfs_iflush() does not keep any references to the inode.
- * We leave that decision up to xfs_iflush() since it has the
- * knowledge of whether it's OK to simply do a delwri flush of
- * the inode or whether we need to wait until the inode is
- * pulled from the AIL.
- * We get the flush lock regardless, though, just to make sure
- * we don't free it while it is being flushed.
- */
- xfs_ilock(ip, XFS_ILOCK_EXCL);
- xfs_iflock(ip);
-
- /*
- * In the case of a forced shutdown we rely on xfs_iflush() to
- * wait for the inode to be unpinned before returning an error.
- */
- if (!is_bad_inode(VFS_I(ip)) && xfs_iflush(ip, sync_mode) == 0) {
- /* synchronize with xfs_iflush_done */
- xfs_iflock(ip);
- xfs_ifunlock(ip);
- }
-
- xfs_iunlock(ip, XFS_ILOCK_EXCL);
- xfs_ireclaim(ip);
- return 0;
-}
-
void
__xfs_inode_set_reclaim_tag(
struct xfs_perag *pag,
@@ -760,19 +708,55 @@
}
STATIC int
-xfs_reclaim_inode_now(
+xfs_reclaim_inode(
struct xfs_inode *ip,
struct xfs_perag *pag,
- int flags)
+ int sync_mode)
{
- /* ignore if already under reclaim */
- if (xfs_iflags_test(ip, XFS_IRECLAIM)) {
- read_unlock(&pag->pag_ici_lock);
+ /*
+ * The radix tree lock here protects a thread in xfs_iget from racing
+ * with us starting reclaim on the inode. Once we have the
+ * XFS_IRECLAIM flag set it will not touch us.
+ */
+ spin_lock(&ip->i_flags_lock);
+ ASSERT_ALWAYS(__xfs_iflags_test(ip, XFS_IRECLAIMABLE));
+ if (__xfs_iflags_test(ip, XFS_IRECLAIM)) {
+ /* ignore as it is already under reclaim */
+ spin_unlock(&ip->i_flags_lock);
+ write_unlock(&pag->pag_ici_lock);
return 0;
}
- read_unlock(&pag->pag_ici_lock);
+ __xfs_iflags_set(ip, XFS_IRECLAIM);
+ spin_unlock(&ip->i_flags_lock);
+ write_unlock(&pag->pag_ici_lock);
- return xfs_reclaim_inode(ip, flags);
+ /*
+ * If the inode is still dirty, then flush it out. If the inode
+ * is not in the AIL, then it will be OK to flush it delwri as
+ * long as xfs_iflush() does not keep any references to the inode.
+ * We leave that decision up to xfs_iflush() since it has the
+ * knowledge of whether it's OK to simply do a delwri flush of
+ * the inode or whether we need to wait until the inode is
+ * pulled from the AIL.
+ * We get the flush lock regardless, though, just to make sure
+ * we don't free it while it is being flushed.
+ */
+ xfs_ilock(ip, XFS_ILOCK_EXCL);
+ xfs_iflock(ip);
+
+ /*
+ * In the case of a forced shutdown we rely on xfs_iflush() to
+ * wait for the inode to be unpinned before returning an error.
+ */
+ if (!is_bad_inode(VFS_I(ip)) && xfs_iflush(ip, sync_mode) == 0) {
+ /* synchronize with xfs_iflush_done */
+ xfs_iflock(ip);
+ xfs_ifunlock(ip);
+ }
+
+ xfs_iunlock(ip, XFS_ILOCK_EXCL);
+ xfs_ireclaim(ip);
+ return 0;
}
int
@@ -780,6 +764,6 @@
xfs_mount_t *mp,
int mode)
{
- return xfs_inode_ag_iterator(mp, xfs_reclaim_inode_now, mode,
- XFS_ICI_RECLAIM_TAG);
+ return xfs_inode_ag_iterator(mp, xfs_reclaim_inode, mode,
+ XFS_ICI_RECLAIM_TAG, 1);
}