David Sterba wrote on 2016/02/22 18:58 +0100:
On Thu, Feb 11, 2016 at 01:24:13PM +0100, David Sterba wrote:
We use the private member of extent_state to store the failrec and play
pointless pointer games.
Signed-off-by: David Sterba <dsterba@xxxxxxxx>
I'm not sure why, but my gcc 5.3.1 think's that a member of failrec can
be used uninitialized:
CC [M] fs/btrfs/extent_io.o
fs/btrfs/extent_io.c: In function ‘clean_io_failure’:
fs/btrfs/extent_io.c:2133:4: warning: ‘failrec’ may be used uninitialized in this function [-Wmaybe-uninitialized]
repair_io_failure(inode, start, failrec->len,
^
After applying your patch on integration-4.6, and compiling, my gcc
5.3.0 didn't give such warning though.
And I didn't see an official 5.3.1, but only 5.3 so I assume maybe it's
related to the .1 from your distribution?
(As my gcc is from Archlinux, I assume minimally patched)
Thanks,
Qu
which points to:
2126 if (state && state->start <= failrec->start &&
2127 state->end >= failrec->start + failrec->len - 1) {
2128 num_copies = btrfs_num_copies(fs_info, failrec->logical,
2129 failrec->len);
2130 if (num_copies > 1) {
2131 repair_io_failure(inode, start, failrec->len,
2132 failrec->logical, page,
2133 pg_offset, failrec->failed_mirror);
2134 }
2135 }
After separating all members to local varaibles, it points to ->len. Which is
used several times in code above.
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