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authorCarlos Maiolino <cmaiolino@redhat.com>2017-09-17 14:06:56 -0700
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2017-09-20 08:20:00 +0200
commit536932f39e93411c48a165c9c859e806c8989301 (patch)
tree21c3df37cc08229c8210ead27b18bd846ee293f8
parent6b6505d90b77f98b0ce08a8332f03cb62f97c78f (diff)
downloadlinux-linaro-stable-536932f39e93411c48a165c9c859e806c8989301.tar.gz
xfs: stop searching for free slots in an inode chunk when there are none
commit 2d32311cf19bfb8c1d2b4601974ddd951f9cfd0b upstream. In a filesystem without finobt, the Space manager selects an AG to alloc a new inode, where xfs_dialloc_ag_inobt() will search the AG for the free slot chunk. When the new inode is in the same AG as its parent, the btree will be searched starting on the parent's record, and then retried from the top if no slot is available beyond the parent's record. To exit this loop though, xfs_dialloc_ag_inobt() relies on the fact that the btree must have a free slot available, once its callers relied on the agi->freecount when deciding how/where to allocate this new inode. In the case when the agi->freecount is corrupted, showing available inodes in an AG, when in fact there is none, this becomes an infinite loop. Add a way to stop the loop when a free slot is not found in the btree, making the function to fall into the whole AG scan which will then, be able to detect the corruption and shut the filesystem down. As pointed by Brian, this might impact performance, giving the fact we don't reset the search distance anymore when we reach the end of the tree, giving it fewer tries before falling back to the whole AG search, but it will only affect searches that start within 10 records to the end of the tree. Signed-off-by: Carlos Maiolino <cmaiolino@redhat.com> Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--fs/xfs/libxfs/xfs_ialloc.c55
1 files changed, 27 insertions, 28 deletions
diff --git a/fs/xfs/libxfs/xfs_ialloc.c b/fs/xfs/libxfs/xfs_ialloc.c
index af6acd5f276c..4536ac588fa3 100644
--- a/fs/xfs/libxfs/xfs_ialloc.c
+++ b/fs/xfs/libxfs/xfs_ialloc.c
@@ -1123,6 +1123,7 @@ xfs_dialloc_ag_inobt(
int error;
int offset;
int i, j;
+ int searchdistance = 10;
pag = xfs_perag_get(mp, agno);
@@ -1149,7 +1150,6 @@ xfs_dialloc_ag_inobt(
if (pagno == agno) {
int doneleft; /* done, to the left */
int doneright; /* done, to the right */
- int searchdistance = 10;
error = xfs_inobt_lookup(cur, pagino, XFS_LOOKUP_LE, &i);
if (error)
@@ -1210,21 +1210,9 @@ xfs_dialloc_ag_inobt(
/*
* Loop until we find an inode chunk with a free inode.
*/
- while (!doneleft || !doneright) {
+ while (--searchdistance > 0 && (!doneleft || !doneright)) {
int useleft; /* using left inode chunk this time */
- if (!--searchdistance) {
- /*
- * Not in range - save last search
- * location and allocate a new inode
- */
- xfs_btree_del_cursor(tcur, XFS_BTREE_NOERROR);
- pag->pagl_leftrec = trec.ir_startino;
- pag->pagl_rightrec = rec.ir_startino;
- pag->pagl_pagino = pagino;
- goto newino;
- }
-
/* figure out the closer block if both are valid. */
if (!doneleft && !doneright) {
useleft = pagino -
@@ -1268,26 +1256,37 @@ xfs_dialloc_ag_inobt(
goto error1;
}
- /*
- * We've reached the end of the btree. because
- * we are only searching a small chunk of the
- * btree each search, there is obviously free
- * inodes closer to the parent inode than we
- * are now. restart the search again.
- */
- pag->pagl_pagino = NULLAGINO;
- pag->pagl_leftrec = NULLAGINO;
- pag->pagl_rightrec = NULLAGINO;
- xfs_btree_del_cursor(tcur, XFS_BTREE_NOERROR);
- xfs_btree_del_cursor(cur, XFS_BTREE_NOERROR);
- goto restart_pagno;
+ if (searchdistance <= 0) {
+ /*
+ * Not in range - save last search
+ * location and allocate a new inode
+ */
+ xfs_btree_del_cursor(tcur, XFS_BTREE_NOERROR);
+ pag->pagl_leftrec = trec.ir_startino;
+ pag->pagl_rightrec = rec.ir_startino;
+ pag->pagl_pagino = pagino;
+
+ } else {
+ /*
+ * We've reached the end of the btree. because
+ * we are only searching a small chunk of the
+ * btree each search, there is obviously free
+ * inodes closer to the parent inode than we
+ * are now. restart the search again.
+ */
+ pag->pagl_pagino = NULLAGINO;
+ pag->pagl_leftrec = NULLAGINO;
+ pag->pagl_rightrec = NULLAGINO;
+ xfs_btree_del_cursor(tcur, XFS_BTREE_NOERROR);
+ xfs_btree_del_cursor(cur, XFS_BTREE_NOERROR);
+ goto restart_pagno;
+ }
}
/*
* In a different AG from the parent.
* See if the most recently allocated block has any free.
*/
-newino:
if (agi->agi_newino != cpu_to_be32(NULLAGINO)) {
error = xfs_inobt_lookup(cur, be32_to_cpu(agi->agi_newino),
XFS_LOOKUP_EQ, &i);