xfs: implement batched inode lookups for AG walking
With the reclaim code separated from the generic walking code, it is
simple to implement batched lookups for the generic walk code.
Separate out the inode validation from the execute operations and
modify the tree lookups to get a batch of inodes at a time.
Reclaim operations will be optimised separately.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-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 37fc2c0..0ed3d0a 100644
--- a/fs/xfs/linux-2.6/xfs_sync.c
+++ b/fs/xfs/linux-2.6/xfs_sync.c
@@ -39,6 +39,14 @@
#include <linux/kthread.h>
#include <linux/freezer.h>
+/*
+ * The inode lookup is done in batches to keep the amount of lock traffic and
+ * radix tree lookups to a minimum. The batch size is a trade off between
+ * lookup reduction and stack usage. This is in the reclaim path, so we can't
+ * be too greedy.
+ */
+#define XFS_LOOKUP_BATCH 32
+
STATIC int
xfs_inode_ag_walk_grab(
struct xfs_inode *ip)
@@ -66,7 +74,6 @@
return 0;
}
-
STATIC int
xfs_inode_ag_walk(
struct xfs_mount *mp,
@@ -79,54 +86,69 @@
int last_error = 0;
int skipped;
int done;
+ int nr_found;
restart:
done = 0;
skipped = 0;
first_index = 0;
+ nr_found = 0;
do {
+ struct xfs_inode *batch[XFS_LOOKUP_BATCH];
int error = 0;
- int nr_found;
- xfs_inode_t *ip;
+ int i;
read_lock(&pag->pag_ici_lock);
nr_found = radix_tree_gang_lookup(&pag->pag_ici_root,
- (void **)&ip, first_index, 1);
+ (void **)batch, first_index,
+ XFS_LOOKUP_BATCH);
if (!nr_found) {
read_unlock(&pag->pag_ici_lock);
break;
}
/*
- * Update the index for the next lookup. Catch overflows
- * into the next AG range which can occur if we have inodes
- * in the last block of the AG and we are currently
- * pointing to the last inode.
+ * Grab the inodes before we drop the lock. if we found
+ * nothing, nr == 0 and the loop will be skipped.
*/
- first_index = XFS_INO_TO_AGINO(mp, ip->i_ino + 1);
- if (first_index < XFS_INO_TO_AGINO(mp, ip->i_ino))
- done = 1;
+ for (i = 0; i < nr_found; i++) {
+ struct xfs_inode *ip = batch[i];
- if (xfs_inode_ag_walk_grab(ip)) {
- read_unlock(&pag->pag_ici_lock);
- continue;
+ if (done || xfs_inode_ag_walk_grab(ip))
+ batch[i] = NULL;
+
+ /*
+ * Update the index for the next lookup. Catch overflows
+ * into the next AG range which can occur if we have inodes
+ * in the last block of the AG and we are currently
+ * pointing to the last inode.
+ */
+ first_index = XFS_INO_TO_AGINO(mp, ip->i_ino + 1);
+ if (first_index < XFS_INO_TO_AGINO(mp, ip->i_ino))
+ done = 1;
}
+
+ /* unlock now we've grabbed the inodes. */
read_unlock(&pag->pag_ici_lock);
- error = execute(ip, pag, flags);
- IRELE(ip);
- if (error == EAGAIN) {
- skipped++;
- continue;
+ for (i = 0; i < nr_found; i++) {
+ if (!batch[i])
+ continue;
+ error = execute(batch[i], pag, flags);
+ IRELE(batch[i]);
+ if (error == EAGAIN) {
+ skipped++;
+ continue;
+ }
+ if (error && last_error != EFSCORRUPTED)
+ last_error = error;
}
- if (error)
- last_error = error;
/* bail out if the filesystem is corrupted. */
if (error == EFSCORRUPTED)
break;
- } while (!done);
+ } while (nr_found && !done);
if (skipped) {
delay(1);