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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.
d77815461f
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>
This commit is contained in:
parent
62e2390e1a
commit
51f395ad40
2 changed files with 5 additions and 6 deletions
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@ -6146,14 +6146,14 @@ static int btrfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
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static int merge_extent_mapping(struct extent_map_tree *em_tree,
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static int merge_extent_mapping(struct extent_map_tree *em_tree,
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struct extent_map *existing,
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struct extent_map *existing,
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struct extent_map *em,
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struct extent_map *em,
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u64 map_start, u64 map_len)
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u64 map_start)
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{
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{
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u64 start_diff;
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u64 start_diff;
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BUG_ON(map_start < em->start || map_start >= extent_map_end(em));
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BUG_ON(map_start < em->start || map_start >= extent_map_end(em));
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start_diff = map_start - em->start;
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start_diff = map_start - em->start;
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em->start = map_start;
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em->start = map_start;
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em->len = map_len;
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em->len = existing->start - em->start;
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if (em->block_start < EXTENT_MAP_LAST_BYTE &&
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if (em->block_start < EXTENT_MAP_LAST_BYTE &&
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!test_bit(EXTENT_FLAG_COMPRESSED, &em->flags)) {
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!test_bit(EXTENT_FLAG_COMPRESSED, &em->flags)) {
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em->block_start += start_diff;
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em->block_start += start_diff;
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@ -6441,8 +6441,7 @@ struct extent_map *btrfs_get_extent(struct inode *inode, struct page *page,
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em->len);
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em->len);
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if (existing) {
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if (existing) {
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err = merge_extent_mapping(em_tree, existing,
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err = merge_extent_mapping(em_tree, existing,
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em, start,
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em, start);
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root->sectorsize);
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free_extent_map(existing);
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free_extent_map(existing);
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if (err) {
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if (err) {
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free_extent_map(em);
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free_extent_map(em);
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