From 7b2b70851f862b68714f357d2926adbb6c574fdd Mon Sep 17 00:00:00 2001 From: Miao Xie Date: Thu, 27 Feb 2014 13:58:05 +0800 Subject: Btrfs: fix preallocate vs double nocow write We can not release the reserved metadata space for the first write if we find the write position is pre-allocated. Because the kernel might write the data on the disk before we do the second write but after the can-nocow check, if we release the space for the first write, we might fail to update the metadata because of no space. Fix this problem by end nocow write if there is dirty data in the range whose space is pre-allocated. Signed-off-by: Miao Xie Signed-off-by: Josef Bacik --- fs/btrfs/inode.c | 16 +++++++++++++++- 1 file changed, 15 insertions(+), 1 deletion(-) (limited to 'fs/btrfs/inode.c') diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index 8dba152883d3..0182f081d499 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -6557,6 +6557,7 @@ noinline int can_nocow_extent(struct inode *inode, u64 offset, u64 *len, int ret; struct extent_buffer *leaf; struct btrfs_root *root = BTRFS_I(inode)->root; + struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree; struct btrfs_file_extent_item *fi; struct btrfs_key key; u64 disk_bytenr; @@ -6633,6 +6634,20 @@ noinline int can_nocow_extent(struct inode *inode, u64 offset, u64 *len, if (btrfs_extent_readonly(root, disk_bytenr)) goto out; + + num_bytes = min(offset + *len, extent_end) - offset; + if (!nocow && found_type == BTRFS_FILE_EXTENT_PREALLOC) { + u64 range_end; + + range_end = round_up(offset + num_bytes, root->sectorsize) - 1; + ret = test_range_bit(io_tree, offset, range_end, + EXTENT_DELALLOC, 0, NULL); + if (ret) { + ret = -EAGAIN; + goto out; + } + } + btrfs_release_path(path); /* @@ -6661,7 +6676,6 @@ noinline int can_nocow_extent(struct inode *inode, u64 offset, u64 *len, */ disk_bytenr += backref_offset; disk_bytenr += offset - key.offset; - num_bytes = min(offset + *len, extent_end) - offset; if (csum_exist_in_range(root, disk_bytenr, num_bytes)) goto out; /* -- cgit v1.2.3