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Commit 69ffb543 authored by Josef Bacik's avatar Josef Bacik Committed by Chris Mason
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Btrfs: create a pinned em when writing to a prealloc range in DIO 



Wade Cline reported a problem where he was getting garbage and warnings when
writing to a preallocated range via O_DIRECT.  This is because we weren't
creating our normal pinned extent_map for the range we were writing to,
which was causing all sorts of issues.  This patch fixes the problem and
makes his testcase much happier.  Thanks,

Reported-by: default avatarWade Cline <clinew@linux.vnet.ibm.com>
Signed-off-by: default avatarJosef Bacik <jbacik@fusionio.com>
parent 6df7881a

fs/btrfs/inode.c

+55 −0
Original line number Diff line number Diff line
@@ -5898,6 +5898,48 @@ static int lock_extent_direct(struct inode *inode, u64 lockstart, u64 lockend, 
	return ret;

}



static struct extent_map *create_pinned_em(struct inode *inode, u64 start,

					   u64 len, u64 orig_start,

					   u64 block_start, u64 block_len,

					   int type)

{

	struct extent_map_tree *em_tree;

	struct extent_map *em;

	struct btrfs_root *root = BTRFS_I(inode)->root;

	int ret;



	em_tree = &BTRFS_I(inode)->extent_tree;

	em = alloc_extent_map();

	if (!em)

		return ERR_PTR(-ENOMEM);



	em->start = start;

	em->orig_start = orig_start;

	em->len = len;

	em->block_len = block_len;

	em->block_start = block_start;

	em->bdev = root->fs_info->fs_devices->latest_bdev;

	set_bit(EXTENT_FLAG_PINNED, &em->flags);

	if (type == BTRFS_ORDERED_PREALLOC)

		set_bit(EXTENT_FLAG_PREALLOC, &em->flags);



	do {

		btrfs_drop_extent_cache(inode, em->start,

				em->start + em->len - 1, 0);

		write_lock(&em_tree->lock);

		ret = add_extent_mapping(em_tree, em);

		write_unlock(&em_tree->lock);

	} while (ret == -EEXIST);



	if (ret) {

		free_extent_map(em);

		return ERR_PTR(ret);

	}



	return em;

}





static int btrfs_get_blocks_direct(struct inode *inode, sector_t iblock,

				   struct buffer_head *bh_result, int create)

{
@@ -6012,6 +6054,19 @@ static int btrfs_get_blocks_direct(struct inode *inode, sector_t iblock, 
			goto must_cow;



		if (can_nocow_odirect(trans, inode, start, len) == 1) {

			u64 orig_start = em->start;



			if (type == BTRFS_ORDERED_PREALLOC) {

				free_extent_map(em);

				em = create_pinned_em(inode, start, len,

						       orig_start,

						       block_start, len, type);

				if (IS_ERR(em)) {

					btrfs_end_transaction(trans, root);

					goto unlock_err;

				}

			}



			ret = btrfs_add_ordered_extent_dio(inode, start,

					   block_start, len, len, type);

			btrfs_end_transaction(trans, root);