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authorFilipe Manana <fdmanana@suse.com>2014-10-17 18:20:08 +0100
committerDavid Sterba <dsterba@suse.cz>2014-10-17 18:24:54 +0200
commit555b7feaebc109bbc184f333779bd664adc34125 (patch)
tree6c1366dfc668186bce1517cb1f94772c1f06169e /disk-io.c
parenta197726ad770760c28a2595cf24ef5cf40f673e0 (diff)
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Btrfs-progs: check, ability to detect and fix outdated snapshot root items
This change adds code to detect and fix the issue introduced in the kernel release 3.17, where creation of read-only snapshots lead to a corrupted filesystem if they were created at a moment when the source subvolume/snapshot had orphan items. The issue was that the on-disk root items became incorrect, referring to the pre orphan cleanup root node instead of the post orphan cleanup root node. A test filesystem can be generated with the test case recently submitted for xfstests/fstests, which is essencially the following (bash script): workout() { ops=$1 procs=$2 num_snapshots=$3 _scratch_mkfs >> $seqres.full 2>&1 _scratch_mount snapshot_cmd="$BTRFS_UTIL_PROG subvolume snapshot -r $SCRATCH_MNT" snapshot_cmd="$snapshot_cmd $SCRATCH_MNT/snap_\`date +'%H_%M_%S_%N'\`" run_check $FSSTRESS_PROG -p $procs \ -x "$snapshot_cmd" -X $num_snapshots -d $SCRATCH_MNT -n $ops } ops=10000 procs=4 snapshots=500 workout $ops $procs $snapshots Example of btrfsck's (btrfs check) behaviour against such filesystem: $ btrfsck /dev/loop0 root item for root 311, current bytenr 44630016, current gen 60, current level 1, new bytenr 44957696, new gen 61, new level 1 root item for root 1480, current bytenr 1003569152, current gen 1271, current level 1, new bytenr 1004175360, new gen 1272, new level 1 root item for root 1509, current bytenr 1037434880, current gen 1300, current level 1, new bytenr 1038467072, new gen 1301, new level 1 root item for root 1562, current bytenr 33636352, current gen 1354, current level 1, new bytenr 34455552, new gen 1355, new level 1 root item for root 3094, current bytenr 1011712000, current gen 2935, current level 1, new bytenr 1008484352, new gen 2936, new level 1 root item for root 3716, current bytenr 80805888, current gen 3578, current level 1, new bytenr 73515008, new gen 3579, new level 1 root item for root 4085, current bytenr 714031104, current gen 3958, current level 1, new bytenr 716816384, new gen 3959, new level 1 Found 7 roots with an outdated root item. Please run a filesystem check with the option --repair to fix them. $ echo $? 1 $ btrfsck --repair /dev/loop0 enabling repair mode fixing root item for root 311, current bytenr 44630016, current gen 60, current level 1, new bytenr 44957696, new gen 61, new level 1 fixing root item for root 1480, current bytenr 1003569152, current gen 1271, current level 1, new bytenr 1004175360, new gen 1272, new level 1 fixing root item for root 1509, current bytenr 1037434880, current gen 1300, current level 1, new bytenr 1038467072, new gen 1301, new level 1 fixing root item for root 1562, current bytenr 33636352, current gen 1354, current level 1, new bytenr 34455552, new gen 1355, new level 1 fixing root item for root 3094, current bytenr 1011712000, current gen 2935, current level 1, new bytenr 1008484352, new gen 2936, new level 1 fixing root item for root 3716, current bytenr 80805888, current gen 3578, current level 1, new bytenr 73515008, new gen 3579, new level 1 fixing root item for root 4085, current bytenr 714031104, current gen 3958, current level 1, new bytenr 716816384, new gen 3959, new level 1 Fixed 7 roots. Checking filesystem on /dev/loop0 UUID: 2186e9b9-c977-4a35-9c7b-69c6609d4620 checking extents checking free space cache cache and super generation don't match, space cache will be invalidated checking fs roots checking csums checking root refs found 618537000 bytes used err is 0 total csum bytes: 130824 total tree bytes: 601620480 total fs tree bytes: 580288512 total extent tree bytes: 18464768 btree space waste bytes: 136939144 file data blocks allocated: 34150318080 referenced 27815415808 Btrfs v3.17-rc3-2-gbbe1dd8 $ echo $? 0 Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: David Sterba <dsterba@suse.cz>
Diffstat (limited to 'disk-io.c')
-rw-r--r--disk-io.c2
1 files changed, 2 insertions, 0 deletions
diff --git a/disk-io.c b/disk-io.c
index 02b6d42..77fc610 100644
--- a/disk-io.c
+++ b/disk-io.c
@@ -475,6 +475,8 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
if (root->commit_root == root->node)
goto commit_tree;
+ if (root == root->fs_info->tree_root)
+ goto commit_tree;
free_extent_buffer(root->commit_root);
root->commit_root = NULL;