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Commit 14543774 authored by Filipe Manana's avatar Filipe Manana
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Btrfs: fix error path when failing to submit bio for direct IO write 



Commit 61de718f ("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: default avatarFilipe Manana <fdmanana@suse.com>
Reviewed-by: default avatarLiu Bo <bo.li.liu@oracle.com>
parent 7785a663

fs/btrfs/inode.c

+27 −27
Original line number Diff line number Diff line
@@ -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 @@ static void btrfs_endio_direct_write(struct bio *bio) 
	 * 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 @@ static void btrfs_submit_direct(int rw, struct bio *dio_bio, 
		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,

						0);

		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()