ext4: fix suboptimal seek_{data,hole} extents traversial

It is ridiculous practice to scan inode block by block, this technique
applicable only for old indirect files. This takes significant amount
of time for really large files. Let's reuse ext4_fiemap which already
traverse inode-tree in most optimal meaner.

TESTCASE:
ftruncate64(fd, 0);
ftruncate64(fd, 1ULL << 40);
/* lseek will spin very long time */
lseek64(fd, 0, SEEK_DATA);
lseek64(fd, 0, SEEK_HOLE);

Original report: https://lkml.org/lkml/2014/10/16/620

Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index bed4308..e5d3ead 100644 (file)
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -5166,8 +5166,8 @@ int ext4_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
 
        /* fallback to generic here if not in extents fmt */
        if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)))
-               return generic_block_fiemap(inode, fieinfo, start, len,
-                       ext4_get_block);
+               return __generic_block_fiemap(inode, fieinfo, start, len,
+                                             ext4_get_block);
 
        if (fiemap_check_flags(fieinfo, EXT4_FIEMAP_FLAGS))
                return -EBADR;

diff --cc fs/ext4/file.c
Simple merge