ext4: treat buffers with write errors as containing valid data (7963e5ac) · Commits · 戴 / test

I got some errors when I repair an ext4 volume which stacked by an iscsi target: Entry 'test60' in / (2) has deleted/unused inode 73750. Clear? It can be reproduced when the network not good enough. When I debug this I found ext4 will read entry buffer from disk and the buffer is marked with write_io_error. If the buffer is marked with write_io_error, it means it already wroten to journal, and not checked out to disk. IOW, the journal is newer than the data in disk. If this journal record 'delete test60', it means the 'test60' still on the disk metadata. In this case, if we read the buffer from disk successfully and create file continue, the new journal record will overwrite the journal which record 'delete test60', then the entry corruptioned. So, use the buffer rather than read from disk if the buffer is marked with write_io_error. Signed-off-by:

Zhang Xiaoxu <zhangxiaoxu5@huawei.com> Signed-off-by:

Theodore Ts'o <tytso@mit.edu>

fs/ext4/ext4.h

+13 −0

Original line number	Diff line number	Diff line
		@@ -3344,6 +3344,19 @@ static inline void ext4_clear_io_unwritten_flag(ext4_io_end_t *io_end)

		extern const struct iomap_ops ext4_iomap_ops;

		static inline int ext4_buffer_uptodate(struct buffer_head *bh)
		{
		/*
		* If the buffer has the write error flag, we have failed
		* to write out data in the block. In this case, we don't
		* have to read the block because we may read the old data
		* successfully.
		*/
		if (!buffer_uptodate(bh) && buffer_write_io_error(bh))
		set_buffer_uptodate(bh);
		return buffer_uptodate(bh);
		}

		#endif /* __KERNEL__ */

		#define EFSBADCRC EBADMSG /* Bad CRC detected */

fs/ext4/inode.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -1024,7 +1024,7 @@ struct buffer_head ext4_bread(handle_t handle, struct inode *inode,
		bh = ext4_getblk(handle, inode, block, map_flags);
		if (IS_ERR(bh))
		return bh;
		if (!bh \|\| buffer_uptodate(bh))
		if (!bh \|\| ext4_buffer_uptodate(bh))
		return bh;
		ll_rw_block(REQ_OP_READ, REQ_META \| REQ_PRIO, 1, &bh);
		wait_on_buffer(bh);
		@@ -1051,7 +1051,7 @@ int ext4_bread_batch(struct inode *inode, ext4_lblk_t block, int bh_count,

		for (i = 0; i < bh_count; i++)
		/* Note that NULL bhs[i] is valid because of holes. */
		if (bhs[i] && !buffer_uptodate(bhs[i]))
		if (bhs[i] && !ext4_buffer_uptodate(bhs[i]))
		ll_rw_block(REQ_OP_READ, REQ_META \| REQ_PRIO, 1,
		&bhs[i]);

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