Btrfs: fix wrong outstanding_extents when doing DIO write
When running the 083th case of xfstests on the filesystem with "compress-force=lzo", the following WARNINGs were triggered. WARNING: at fs/btrfs/inode.c:7908 WARNING: at fs/btrfs/inode.c:7909 WARNING: at fs/btrfs/inode.c:7911 WARNING: at fs/btrfs/extent-tree.c:4510 WARNING: at fs/btrfs/extent-tree.c:4511 This problem was introduced by the patch "Btrfs: fix deadlock due to unsubmitted". In this patch, there are two bugs which caused the above problem. The 1st one is a off-by-one bug, if the DIO write return 0, it is also a short write, we need release the reserved space for it. But we didn't do it in that patch. Fix it by change "ret > 0" to "ret >= 0". The 2nd one is ->outstanding_extents was increased twice when a short write happened. As we know, ->outstanding_extents is a counter to keep track of the number of extent items we may use duo to delalloc, when we reserve the free space for a delalloc write, we assume that the write will introduce just one extent item, so we increase ->outstanding_extents by 1 at that time. And then we will increase it every time we split the write, it is done at the beginning of btrfs_get_blocks_direct(). So when a short write happens, we needn't increase ->outstanding_extents again. But this patch done. In order to fix the 2nd problem, I re-write the logic for ->outstanding_extents operation. We don't increase it at the beginning of btrfs_get_blocks_direct(), instead, we just increase it when the split actually happens. Reported-by: Mitch Harder <mitch.harder@sabayonlinux.org> Signed-off-by: Miao Xie <miaox@cn.fujitsu.com> Signed-off-by: Chris Mason <chris.mason@fusionio.com>
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38c227d87c
Коммит
172a50497f
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@ -6708,12 +6708,9 @@ static int btrfs_get_blocks_direct(struct inode *inode, sector_t iblock,
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int unlock_bits = EXTENT_LOCKED;
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int ret = 0;
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if (create) {
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spin_lock(&BTRFS_I(inode)->lock);
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BTRFS_I(inode)->outstanding_extents++;
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spin_unlock(&BTRFS_I(inode)->lock);
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if (create)
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unlock_bits |= EXTENT_DELALLOC | EXTENT_DIRTY;
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} else
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else
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len = min_t(u64, len, root->sectorsize);
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lockstart = start;
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@ -6855,6 +6852,10 @@ unlock:
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if (start + len > i_size_read(inode))
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i_size_write(inode, start + len);
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spin_lock(&BTRFS_I(inode)->lock);
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BTRFS_I(inode)->outstanding_extents++;
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spin_unlock(&BTRFS_I(inode)->lock);
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ret = set_extent_bit(&BTRFS_I(inode)->io_tree, lockstart,
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lockstart + len - 1, EXTENT_DELALLOC, NULL,
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&cached_state, GFP_NOFS);
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@ -7362,14 +7363,11 @@ static ssize_t btrfs_direct_IO(int rw, struct kiocb *iocb,
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if (rw & WRITE) {
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if (ret < 0 && ret != -EIOCBQUEUED)
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btrfs_delalloc_release_space(inode, count);
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else if (ret > 0 && (size_t)ret < count) {
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spin_lock(&BTRFS_I(inode)->lock);
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BTRFS_I(inode)->outstanding_extents++;
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spin_unlock(&BTRFS_I(inode)->lock);
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else if (ret >= 0 && (size_t)ret < count)
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btrfs_delalloc_release_space(inode,
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count - (size_t)ret);
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}
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btrfs_delalloc_release_metadata(inode, 0);
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else
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btrfs_delalloc_release_metadata(inode, 0);
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}
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out:
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if (wakeup)
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