filefrag has several bugs:
1.
$ touch f1
$ filefrag f1
f1: 1 extent found ----> bug!
$ filefrag -v f1
Filesystem type is: ef53
File size of f1 is 0 (0 blocks, blocksize 4096)
f1: 0 extents found
2.
$ truncate -s 1m f2
$ filefrag f2
f2: 1 extent found ----> bug!
$ filefrag -v f2
Filesystem type is: ef53
File size of f2 is 1048576 (256 blocks, blocksize 4096)
f2: 0 extents found
3.
$ for i in `seq 11 -2 0`; do dd if=/dev/zero of=f4 bs=4k count=1 seek=$i conv=notrunc oflag=sync &>/dev/null; done
$ ll f4
-rw-r--r-- 1 root root 49152 Jun 9 15:09 f4
$ filefrag f4
f4: 7 extents found
$ filefrag -v f4
Filesystem type is: ef53
File size of f4 is 49152 (12 blocks, blocksize 4096)
ext logical physical expected length flags
0 1 1109993 1
1 3 1109992 1109994 1
2 5 1109991 1109993 1
3 7 1109990 1109992 1
4 9 1109989 1109991 1
5 11 1108207 1109990 1 eof
f4: 7 extents found --------------------------> but we only have 6 extents, bug!
All of these bugs come from the fact that we've made a mistake on calculating
total extents:
o we set 1 as default for 'total extents', and this will report 1 extent found
even when we don't get any extent from fiemap.
o if our first extent does not start from 0(logical addr), total extents will
be one more than what it should be.
Signed-off-by: Liu Bo <liubo2009@xxxxxxxxxxxxxx>
---
misc/filefrag.c | 25 ++++++++++---------------
1 files changed, 10 insertions(+), 15 deletions(-)
diff --git a/misc/filefrag.c b/misc/filefrag.c
index 0583e91..af008fb 100644
--- a/misc/filefrag.c
+++ b/misc/filefrag.c
@@ -175,7 +175,7 @@ static int filefrag_fiemap(int fd, int blk_shift, int *num_extents)
unsigned int i;
static int fiemap_incompat_printed;
int fiemap_header_printed = 0;
- int tot_extents = 1, n = 0;
+ int tot_extents = 0, n = 0;
int last = 0;
int rc;
@@ -201,25 +201,17 @@ static int filefrag_fiemap(int fd, int blk_shift, int *num_extents)
return rc;
}
+ /* If 0 extents are returned, then more ioctls are not needed */
+ if (fiemap->fm_mapped_extents == 0)
+ break;
+
if (verbose && !fiemap_header_printed) {
- /*
- * No extents on first call?
- * Skip header and show 0 extents.
- */
- if (fiemap->fm_mapped_extents == 0) {
- *num_extents = 0;
- goto out;
- }
printf(" ext %*s %*s %*s length flags\n", logical_width,
"logical", physical_width, "physical",
physical_width, "expected");
fiemap_header_printed = 1;
}
- /* If 0 extents are returned, then more ioctls are not needed */
- if (fiemap->fm_mapped_extents == 0)
- break;
-
for (i = 0; i < fiemap->fm_mapped_extents; i++) {
__u64 phy_blk, logical_blk;
unsigned long ext_len;
@@ -228,10 +220,13 @@ static int filefrag_fiemap(int fd, int blk_shift, int *num_extents)
ext_len = fm_ext[i].fe_length >> blk_shift;
logical_blk = fm_ext[i].fe_logical >> blk_shift;
- if (logical_blk && phy_blk != expected)
+ if (logical_blk && phy_blk != expected) {
tot_extents++;
- else
+ } else {
expected = 0;
+ if (!tot_extents)
+ tot_extents = 1;
+ }
if (verbose)
print_extent_info(&fm_ext[i], n, expected,
blk_shift);
--
1.6.5.2
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