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authorQu Wenruo <quwenruo@cn.fujitsu.com>2014-08-08 13:06:20 +0800
committerChris Mason <clm@fb.com>2014-08-21 07:55:27 -0700
commit51f395ad4058883e4273b02fdebe98072dbdc0d2 (patch)
tree34f6012ce23157db296f2cd668f809b46a4b6d17 /fs/btrfs
parent62e2390e1ad78f956e96a6a831761adc6f2bf58a (diff)
btrfs: Use right extent length when inserting overlap extent map.
When current btrfs finds that a new extent map is going to be insereted but failed with -EEXIST, it will try again to insert the extent map but with the length of sectorsize. This is OK if we don't enable 'no-holes' feature since all extent space is continuous, we will not go into the not found->insert routine. But if we enable 'no-holes' feature, it will make things out of control. e.g. in 4K sectorsize, we pass the following args to btrfs_get_extent(): btrfs_get_extent() args: start: 27874 len 4100 28672 27874 28672 27874+4100 32768 |-----------------------| |---------hole--------------------|---------data----------| 1) not found and insert Since no extent map containing the range, btrfs_get_extent() will go into the not_found and insert routine, which will try to insert the extent map (27874, 27847 + 4100). 2) first overlap But it overlaps with (28672, 32768) extent, so -EEXIST will be returned by add_extent_mapping(). 3) retry but still overlap After catching the -EEXIST, then btrfs_get_extent() will try insert it again but with 4K length, which still overlaps, so -EEXIST will be returned. This makes the following patch fail to punch hole. d77815461f047e561f77a07754ae923ade597d4e btrfs: Avoid trucating page or punching hole in a already existed hole. This patch will use the right length, which is the (exsisting->start - em->start) to insert, making the above patch works in 'no-holes' mode. Also, some small code style problems in above patch is fixed too. Reported-by: Filipe David Manana <fdmanana@gmail.com> Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com> Reviewed-by: Filipe David Manana <fdmanana@suse.com> Tested-by: Filipe David Manana <fdmanana@suse.com> Signed-off-by: Chris Mason <clm@fb.com>
Diffstat (limited to 'fs/btrfs')
-rw-r--r--fs/btrfs/file.c4
-rw-r--r--fs/btrfs/inode.c7
2 files changed, 5 insertions, 6 deletions
diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index 77e33534c7d6..f15c13f97018 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -2215,7 +2215,7 @@ static int btrfs_punch_hole(struct inode *inode, loff_t offset, loff_t len)
goto out_only_mutex;
}
- lockstart = round_up(offset , BTRFS_I(inode)->root->sectorsize);
+ lockstart = round_up(offset, BTRFS_I(inode)->root->sectorsize);
lockend = round_down(offset + len,
BTRFS_I(inode)->root->sectorsize) - 1;
same_page = ((offset >> PAGE_CACHE_SHIFT) ==
@@ -2276,7 +2276,7 @@ static int btrfs_punch_hole(struct inode *inode, loff_t offset, loff_t len)
tail_start + tail_len, 0, 1);
if (ret)
goto out_only_mutex;
- }
+ }
}
}
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 2ac260d41ccd..ae98df67950f 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -6146,14 +6146,14 @@ out_fail:
static int merge_extent_mapping(struct extent_map_tree *em_tree,
struct extent_map *existing,
struct extent_map *em,
- u64 map_start, u64 map_len)
+ u64 map_start)
{
u64 start_diff;
BUG_ON(map_start < em->start || map_start >= extent_map_end(em));
start_diff = map_start - em->start;
em->start = map_start;
- em->len = map_len;
+ em->len = existing->start - em->start;
if (em->block_start < EXTENT_MAP_LAST_BYTE &&
!test_bit(EXTENT_FLAG_COMPRESSED, &em->flags)) {
em->block_start += start_diff;
@@ -6441,8 +6441,7 @@ insert:
em->len);
if (existing) {
err = merge_extent_mapping(em_tree, existing,
- em, start,
- root->sectorsize);
+ em, start);
free_extent_map(existing);
if (err) {
free_extent_map(em);