xfs: add buffer pre-write callback (cfb02852) · Commits · 戴 / test

Add a callback to the buffer write path to enable verification of the buffer and CRC calculation prior to issuing the write to the underlying storage. If the callback function detects some kind of failure or error condition, it must mark the buffer with an error so that the caller can take appropriate action. In the case of xfs_buf_ioapply(), a corrupt metadta buffer willt rigger a shutdown of the filesystem, because something is clearly wrong and we can't allow corrupt metadata to be written to disk. Signed-off-by:

Dave Chinner <dchinner@redhat.com> Reviewed-by:

Phil White <pwhite@sgi.com> Signed-off-by:

Ben Myers <bpm@sgi.com>

fs/xfs/xfs_buf.c

+16 −0

Original line number	Diff line number	Diff line
		@@ -569,7 +569,9 @@ found:
		*/
		if (bp->b_flags & XBF_STALE) {
		ASSERT((bp->b_flags & _XBF_DELWRI_Q) == 0);
		ASSERT(bp->b_iodone == NULL);
		bp->b_flags &= _XBF_KMEM \| _XBF_PAGES;
		bp->b_pre_io = NULL;
		}

		trace_xfs_buf_find(bp, flags, _RET_IP_);
		@@ -1323,6 +1325,20 @@ _xfs_buf_ioapply(
		/* we only use the buffer cache for meta-data */
		rw \|= REQ_META;

		/*
		* run the pre-io callback function if it exists. If this function
		* fails it will mark the buffer with an error and the IO should
		* not be dispatched.
		*/
		if (bp->b_pre_io) {
		bp->b_pre_io(bp);
		if (bp->b_error) {
		xfs_force_shutdown(bp->b_target->bt_mount,
		SHUTDOWN_CORRUPT_INCORE);
		return;
		}
		}

		/*
		* Walk all the vectors issuing IO on them. Set up the initial offset
		* into the buffer and the desired IO size before we start -

fs/xfs/xfs_buf.h

+3 −0

Original line number	Diff line number	Diff line
		@@ -155,6 +155,9 @@ typedef struct xfs_buf {
		unsigned int b_offset; /* page offset in first page */
		unsigned short b_error; /* error code on I/O */

		void (b_pre_io)(struct xfs_buf );
		/* pre-io callback function */

		#ifdef XFS_BUF_LOCK_TRACKING
		int b_last_holder;
		#endif

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