On Tue, Jun 02, 2009 at 08:12:41PM +0800, Peng Tao wrote:
> Some ioctl() returns non-negative value on success. filefrag_fiemap should
> treat positive ioctl() return values as success.
> This can be triggered by running filefrag on btrfs partitions.
Thanks for reporting this!
It turns out that wasn't the only bug in that code; the syscall
infrastructure will take a negative return value and maps that to -1,
and moves the (negative) error code to a positive value in errno. So
the more appropriate patch is as follows.
- Ted
commit e78968f7a42fb1fa75c356dd323d957b307b887f
Author: Theodore Ts'o <tytso@xxxxxxx>
Date: Tue Jun 2 08:45:22 2009 -0400
filefrag: Fix error checking for the fiemap ioctl
Thanks to Peng Tao for reporting this problem.
Signed-off-by: "Theodore Ts'o" <tytso@xxxxxxx>
diff --git a/misc/filefrag.c b/misc/filefrag.c
index 80ac05c..7095949 100644
--- a/misc/filefrag.c
+++ b/misc/filefrag.c
@@ -201,15 +201,14 @@ int filefrag_fiemap(int fd, int blk_shift, int *num_extents)
fiemap->fm_flags = flags;
fiemap->fm_extent_count = count;
rc = ioctl(fd, FS_IOC_FIEMAP, (unsigned long) fiemap);
- if (rc == -EBADR) {
- if (fiemap_incompat_printed == 0) {
+ if (rc < 0) {
+ if (errno == EBADR && fiemap_incompat_printed == 0) {
printf("FIEMAP failed with unsupported "
"flags %x\n", fiemap->fm_flags);
fiemap_incompat_printed = 1;
}
- }
- if (rc)
return rc;
+ }
if (!verbose) {
*num_extents = fiemap->fm_mapped_extents;
--
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