| Message ID | 1434375680-4115-2-git-send-email-jeffm@suse.com (mailing list archive) |
|---|---|
| State | Accepted |
| Headers | show |
On Mon, Jun 15, 2015 at 2:41 PM, <jeffm@suse.com> wrote: > From: Jeff Mahoney <jeffm@suse.com> > > It's possible, though unexpected, to pass unaligned offsets and lengths > to btrfs_issue_discard. We then shift the offset/length values to sector > units. If an unaligned offset has been passed, it will result in the > entire sector being discarded, possibly losing data. An unaligned > length is safe but we'll end up returning an inaccurate number of > discarded bytes. > > This patch aligns the offset to the 512B boundary, adjusts the length, > and warns, since we shouldn't be discarding on an offset that isn't > aligned with our sector size. > > Signed-off-by: Jeff Mahoney <jeffm@suse.com> Reviewed-by: Filipe Manana <fdmanana@suse.com> Tested-by: Filipe Manana <fdmanana@suse.com> > --- > fs/btrfs/extent-tree.c | 17 +++++++++++++---- > 1 file changed, 13 insertions(+), 4 deletions(-) > > diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c > index da1145d..cf9cefd 100644 > --- a/fs/btrfs/extent-tree.c > +++ b/fs/btrfs/extent-tree.c > @@ -1888,12 +1888,21 @@ static int btrfs_issue_discard(struct block_device *bdev, u64 start, u64 len, > u64 *discarded_bytes) > { > int ret = 0; > + u64 aligned_start = ALIGN(start, 1 << 9); > > - *discarded_bytes = 0; > - ret = blkdev_issue_discard(bdev, start >> 9, len >> 9, GFP_NOFS, 0); > - if (!ret) > - *discarded_bytes = len; > + if (WARN_ON(start != aligned_start)) { > + len -= aligned_start - start; > + len = round_down(len, 1 << 9); > + start = aligned_start; > + } > > + *discarded_bytes = 0; > + if (len) { > + ret = blkdev_issue_discard(bdev, start >> 9, len >> 9, > + GFP_NOFS, 0); > + if (!ret) > + *discarded_bytes = len; > + } > return ret; > } > > -- > 2.4.3 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c index da1145d..cf9cefd 100644 --- a/fs/btrfs/extent-tree.c +++ b/fs/btrfs/extent-tree.c @@ -1888,12 +1888,21 @@ static int btrfs_issue_discard(struct block_device *bdev, u64 start, u64 len, u64 *discarded_bytes) { int ret = 0; + u64 aligned_start = ALIGN(start, 1 << 9); - *discarded_bytes = 0; - ret = blkdev_issue_discard(bdev, start >> 9, len >> 9, GFP_NOFS, 0); - if (!ret) - *discarded_bytes = len; + if (WARN_ON(start != aligned_start)) { + len -= aligned_start - start; + len = round_down(len, 1 << 9); + start = aligned_start; + } + *discarded_bytes = 0; + if (len) { + ret = blkdev_issue_discard(bdev, start >> 9, len >> 9, + GFP_NOFS, 0); + if (!ret) + *discarded_bytes = len; + } return ret; }