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由 Miao Xie 提交于
Steps to reproduce: # mkfs.btrfs <disk> # mount <disk> <mnt> # dd if=/dev/zero of=<mnt>/<file> bs=512 seek=5 count=8 # fallocate -p -o 2048 -l 16384 <mnt>/<file> # dd if=/dev/zero of=<mnt>/<file> bs=4096 seek=3 count=8 conv=notrunc,nocreat # umount <mnt> # dmesg WARNING: at fs/btrfs/inode.c:7140 btrfs_destroy_inode+0x2eb/0x330 The reason is that we inputed a range which is beyond the end of the file. And because the end of this range was not page-aligned, we had to truncate the last page in this range, this operation is similar to a buffered file write. In other words, we reserved enough space and clear the data which was in the hole range on that page. But when we expanded that test file, write the data into the same page, we forgot that we have reserved enough space for the buffered write of that page because in most cases there is no page that is beyond the end of the file. As a result, we reserved the space twice. In fact, we needn't truncate the page if it is beyond the end of the file, just release the allocated space in that range. Fix the above problem by this way. Signed-off-by: NMiao Xie <miaox@cn.fujitsu.com> Signed-off-by: NChris Mason <chris.mason@fusionio.com>
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