Re: [PATCH 1/2] btrfs: use correct offset for reloc_inode in prealloc_file_extent_cluster()

[Wang Xiaoguang]

hello,

On 07/07/2016 03:54 AM, Liu Bo wrote:

On Wed, Jul 06, 2016 at 06:37:52PM +0800, Wang Xiaoguang wrote:

In prealloc_file_extent_cluster(), btrfs_check_data_free_space() uses
wrong file offset for reloc_inode, it uses cluster->start and cluster->end,
which indeed are extent's bytenr. The correct value should be
cluster->[start|end] minus block group's start bytenr.

start bytenr   cluster->start
|              |     extent      |   extent   | ...| extent |
|----------------------------------------------------------------|
|                block group reloc_inode                         |

Signed-off-by: Wang Xiaoguang <wangxg.f...@cn.fujitsu.com>
---
  fs/btrfs/relocation.c | 27 +++++++++++++++------------
  1 file changed, 15 insertions(+), 12 deletions(-)

diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c
index 0477dca..abc2f69 100644
--- a/fs/btrfs/relocation.c
+++ b/fs/btrfs/relocation.c
@@ -3030,34 +3030,37 @@ int prealloc_file_extent_cluster(struct inode *inode,
        u64 num_bytes;
        int nr = 0;
        int ret = 0;
+       u64 prealloc_start, prealloc_end;

BUG_ON(cluster->start != cluster->boundary[0]);

        inode_lock(inode);

- ret = btrfs_check_data_free_space(inode, cluster->start,

-                                         cluster->end + 1 - cluster->start);
+       start = cluster->start - offset;
+       end = cluster->end - offset;
+       ret = btrfs_check_data_free_space(inode, start, end + 1 - start);
        if (ret)
                goto out;

while (nr < cluster->nr) {

-               start = cluster->boundary[nr] - offset;
+               prealloc_start = cluster->boundary[nr] - offset;
                if (nr + 1 < cluster->nr)
-                       end = cluster->boundary[nr + 1] - 1 - offset;
+                       prealloc_end = cluster->boundary[nr + 1] - 1 - offset;
                else
-                       end = cluster->end - offset;
+                       prealloc_end = cluster->end - offset;

- lock_extent(&BTRFS_I(inode)->io_tree, start, end);

-               num_bytes = end + 1 - start;
-               ret = btrfs_prealloc_file_range(inode, 0, start,
+               lock_extent(&BTRFS_I(inode)->io_tree, prealloc_start,
+                           prealloc_end);
+               num_bytes = prealloc_end + 1 - prealloc_start;
+               ret = btrfs_prealloc_file_range(inode, 0, prealloc_start,
                                                num_bytes, num_bytes,
-                                               end + 1, &alloc_hint);
-               unlock_extent(&BTRFS_I(inode)->io_tree, start, end);
+                                               prealloc_end + 1, &alloc_hint);
+               unlock_extent(&BTRFS_I(inode)->io_tree, prealloc_start,
+                             prealloc_end);

Changing names is unnecessary, we can pick up other names for 
btrfs_{check/free}_data_free_space().

OK, then the changes will be small, thanks.

Regards,
Xiaoguang Wang

Thanks,

-liubo

                if (ret)
                        break;
                nr++;
        }
-       btrfs_free_reserved_data_space(inode, cluster->start,
-                                      cluster->end + 1 - cluster->start);
+       btrfs_free_reserved_data_space(inode, start, end + 1 - start);
  out:
        inode_unlock(inode);
        return ret;
--
2.9.0



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