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btrfs-progs: convert: Fix offset-by-one error in read_data_extent() 

For read_data_extent() in convert/main.c it's using mirror number in a
incorrect way, which will not get correct copy for RAID1:

	for (cur_mirror = 0; cur_mirror < num_copies; cur_mirror++) {

In such case, for RAID1 @cur_mirror will only be 0 and 1.

However for 0 and 1 case, btrfs_map_block() will only return the first
copy.  To reach the 2nd copy, it correct @cur_mirror range should be 1
and 2.

So with this off-by-one error, btrfs-image will never be able to read
out data extent if the first stripe of the chunk is the missing one.

Fix it by starting @cur_mirror from 1 and to @num_copies (including).

Fixes: 2d46558b30 ("btrfs-progs: Use existing facility to replace read_data_extent function")
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Qu Wenruo 2018-03-30 15:35:27 +08:00 committed by David Sterba
parent 64f3dc0136
commit 6af3cc08dd
1 changed files with 1 additions and 1 deletions
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2
image/main.c
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@ -571,7 +571,7 @@ static int read_data_extent(struct metadump_struct *md,
num_copies = btrfs_num_copies(root->fs_info, logical, bytes_left);
/* Try our best to read data, just like read_tree_block() */
for (cur_mirror = 0; cur_mirror < num_copies; cur_mirror++) {
for (cur_mirror = 1; cur_mirror <= num_copies; cur_mirror++) {
while (bytes_left) {
read_len = bytes_left;
ret = read_extent_data(fs_info,