[PATCH 37/49] ext4: down i_data_sem only for read when walking tree for fiemap

From: Theodore Ts'o
Date: Mon Jun 08 2009 - 15:28:43 EST

Not sure why I put this in as down_write originally; all we are
doing is walking the tree, nothing will change under us and
concurrent reads should be no problem.

Signed-off-by: Eric Sandeen <sandeen@xxxxxxxxxx>
Signed-off-by: "Theodore Ts'o" <tytso@xxxxxxx>
fs/ext4/extents.c | 4 ++--
1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index d04b779..d4e99e9 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -3312,10 +3312,10 @@ int ext4_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
* Walk the extent tree gathering extent information.
* ext4_ext_fiemap_cb will push extents back to user.
- down_write(&EXT4_I(inode)->i_data_sem);
+ down_read(&EXT4_I(inode)->i_data_sem);
error = ext4_ext_walk_space(inode, start_blk, len_blks,
ext4_ext_fiemap_cb, fieinfo);
- up_write(&EXT4_I(inode)->i_data_sem);
+ up_read(&EXT4_I(inode)->i_data_sem);

return error;

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