On Tue, Nov 24, 2015 at 05:25:18PM +0000, fdmanana@xxxxxxxxxx wrote:
> From: Filipe Manana <fdmanana@xxxxxxxx>
>
> Commit 61de718fceb6 ("Btrfs: fix memory corruption on failure to submit
> bio for direct IO") fixed problems with the error handling code after we
> fail to submit a bio for direct IO. However there were 2 problems that it
> did not address when the failure is due to memory allocation failures for
> direct IO writes:
>
> 1) We considered that there could be only one ordered extent for the whole
> IO range, which is not always true, as we can have multiple;
>
> 2) It did not set the bit BTRFS_ORDERED_IO_DONE in the ordered extent,
> which can make other tasks running btrfs_wait_logged_extents() hang
> forever, since they wait for that bit to be set. The general assumption
> is that regardless of an error, the BTRFS_ORDERED_IO_DONE is always set
> and it precedes setting the bit BTRFS_ORDERED_COMPLETE.
>
> Fix these issues by moving part of the btrfs_endio_direct_write() handler
> into a new helper function and having that new helper function called when
> we fail to allocate memory to submit the bio (and its private object) for
> a direct IO write.
>
> Signed-off-by: Filipe Manana <fdmanana@xxxxxxxx>
> ---
> fs/btrfs/inode.c | 54 +++++++++++++++++++++++++++---------------------------
> 1 file changed, 27 insertions(+), 27 deletions(-)
>
> diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
> index f82d1f4..4f8560c 100644
> --- a/fs/btrfs/inode.c
> +++ b/fs/btrfs/inode.c
> @@ -7995,22 +7995,22 @@ static void btrfs_endio_direct_read(struct bio *bio)
> bio_put(bio);
> }
>
> -static void btrfs_endio_direct_write(struct bio *bio)
> +static void btrfs_endio_direct_write_update_ordered(struct inode *inode,
> + const u64 offset,
> + const u64 bytes,
> + const int uptodate)
> {
> - struct btrfs_dio_private *dip = bio->bi_private;
> - struct inode *inode = dip->inode;
> struct btrfs_root *root = BTRFS_I(inode)->root;
> struct btrfs_ordered_extent *ordered = NULL;
> - u64 ordered_offset = dip->logical_offset;
> - u64 ordered_bytes = dip->bytes;
> - struct bio *dio_bio;
> + u64 ordered_offset = offset;
> + u64 ordered_bytes = bytes;
> int ret;
>
> again:
> ret = btrfs_dec_test_first_ordered_pending(inode, &ordered,
> &ordered_offset,
> ordered_bytes,
> - !bio->bi_error);
> + uptodate);
> if (!ret)
> goto out_test;
>
> @@ -8023,13 +8023,22 @@ out_test:
> * our bio might span multiple ordered extents. If we haven't
> * completed the accounting for the whole dio, go back and try again
> */
> - if (ordered_offset < dip->logical_offset + dip->bytes) {
> - ordered_bytes = dip->logical_offset + dip->bytes -
> - ordered_offset;
> + if (ordered_offset < offset + bytes) {
> + ordered_bytes = offset + bytes - ordered_offset;
> ordered = NULL;
> goto again;
> }
> - dio_bio = dip->dio_bio;
> +}
> +
> +static void btrfs_endio_direct_write(struct bio *bio)
> +{
> + struct btrfs_dio_private *dip = bio->bi_private;
> + struct bio *dio_bio = dip->dio_bio;
> +
> + btrfs_endio_direct_write_update_ordered(dip->inode,
> + dip->logical_offset,
> + dip->bytes,
> + !bio->bi_error);
>
> kfree(dip);
>
> @@ -8365,24 +8374,15 @@ free_ordered:
> dip = NULL;
> io_bio = NULL;
> } else {
> - if (write) {
> - struct btrfs_ordered_extent *ordered;
> -
> - ordered = btrfs_lookup_ordered_extent(inode,
> - file_offset);
> - set_bit(BTRFS_ORDERED_IOERR, &ordered->flags);
> - /*
> - * Decrements our ref on the ordered extent and removes
> - * the ordered extent from the inode's ordered tree,
> - * doing all the proper resource cleanup such as for the
> - * reserved space and waking up any waiters for this
> - * ordered extent (through btrfs_remove_ordered_extent).
> - */
> - btrfs_finish_ordered_io(ordered);
> - } else {
> + if (write)
> + btrfs_endio_direct_write_update_ordered(inode,
> + file_offset,
> + dio_bio->bi_iter.bi_size,
> + 1);
uptodate=1 won't set IOERR for ordered extent, is that expected?
Thanks,
-liubo
> + else
> unlock_extent(&BTRFS_I(inode)->io_tree, file_offset,
> file_offset + dio_bio->bi_iter.bi_size - 1);
> - }
> +
> dio_bio->bi_error = -EIO;
> /*
> * Releases and cleans up our dio_bio, no need to bio_put()
> --
> 2.1.3
>
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