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Commit 40095b64 authored by David Chinner's avatar David Chinner Committed by Tim Shimmin
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[XFS] Sleeping with the ilock waiting for I/O completion is Bad. 



Recent fixes to the filesystem freezing code introduced a vn_iowait call
in the middle of the sync code. Unfortunately, at the point where this
call was added we are holding the ilock. The ilock is needed by I/O
completion for unwritten extent conversion and now updating the file size.
Hence I/o cannot complete if we hold the ilock while waiting for I/O
completion.

Fix up the bug and clean the code up around it.

SGI-PV: 963674
SGI-Modid: xfs-linux-melb:xfs-kern:28566a

Signed-off-by: default avatarDavid Chinner <dgc@sgi.com>
Signed-off-by: default avatarChristoph Hellwig <hch@infradead.org>
Signed-off-by: default avatarTim Shimmin <tes@sgi.com>
parent 4cc929ee

fs/xfs/xfs_vfsops.c

+28 −45
Original line number Diff line number Diff line
@@ -1128,51 +1128,31 @@ xfs_sync_inodes( 
		 * in the inode list.

		 */



		if ((flags & SYNC_CLOSE)  && (vp != NULL)) {

		/*

			 * This is the shutdown case.  We just need to

			 * flush and invalidate all the pages associated

			 * with the inode.  Drop the inode lock since

			 * we can't hold it across calls to the buffer

			 * cache.

			 *

			 * We don't set the VREMAPPING bit in the vnode

			 * here, because we don't hold the vnode lock

			 * exclusively.  It doesn't really matter, though,

			 * because we only come here when we're shutting

			 * down anyway.

			 */

			xfs_iunlock(ip, XFS_ILOCK_SHARED);



			if (XFS_FORCED_SHUTDOWN(mp)) {

				bhv_vop_toss_pages(vp, 0, -1, FI_REMAPF);

			} else {

				error = bhv_vop_flushinval_pages(vp, 0, -1, FI_REMAPF);

			}



			xfs_ilock(ip, XFS_ILOCK_SHARED);



		} else if ((flags & SYNC_DELWRI) && (vp != NULL)) {

			if (VN_DIRTY(vp)) {

				/* We need to have dropped the lock here,

				 * so insert a marker if we have not already

				 * done so.

		 * If we have to flush data or wait for I/O completion

		 * we need to drop the ilock that we currently hold.

		 * If we need to drop the lock, insert a marker if we

		 * have not already done so.

		 */

		if ((flags & (SYNC_CLOSE|SYNC_IOWAIT)) ||

		    ((flags & SYNC_DELWRI) && VN_DIRTY(vp))) {

			if (mount_locked) {

				IPOINTER_INSERT(ip, mp);

			}



				/*

				 * Drop the inode lock since we can't hold it

				 * across calls to the buffer cache.

				 */

			xfs_iunlock(ip, XFS_ILOCK_SHARED);



			if (flags & SYNC_CLOSE) {

				/* Shutdown case. Flush and invalidate. */

				if (XFS_FORCED_SHUTDOWN(mp))

					bhv_vop_toss_pages(vp, 0, -1, FI_REMAPF);

				else

					error = bhv_vop_flushinval_pages(vp, 0,

								-1, FI_REMAPF);

			} else if ((flags & SYNC_DELWRI) && VN_DIRTY(vp)) {

				error = bhv_vop_flush_pages(vp, (xfs_off_t)0,

							-1, fflag, FI_NONE);

				xfs_ilock(ip, XFS_ILOCK_SHARED);

			}



		}

			/*

			 * When freezing, we need to wait ensure all I/O (including direct

			 * I/O) is complete to ensure no further data modification can take
@@ -1181,6 +1161,9 @@ xfs_sync_inodes( 
			if (flags & SYNC_IOWAIT)

				vn_iowait(vp);



			xfs_ilock(ip, XFS_ILOCK_SHARED);

		}



		if (flags & SYNC_BDFLUSH) {

			if ((flags & SYNC_ATTR) &&

			    ((ip->i_update_core) ||