From e424aa5f547d2510f8ea1199e7b4ed8ef2d9439d Mon Sep 17 00:00:00 2001 From: "Darrick J. Wong" Date: Mon, 22 Mar 2021 09:51:50 -0700 Subject: xfs: drop freeze protection when running GETFSMAP A recent log refactoring patchset from Brian Foster relaxed fsfreeze behavior with regards to the buffer cache -- now freeze only waits for pending buffer IO to finish, and does not try to drain the buffer cache LRU. As a result, fsfreeze should no longer stall indefinitely while fsmap runs. Drop the sb_start_write calls around fsmap invocations. While we're cleaning things, add a comment to the xfs_trans_alloc_empty call explaining why we're running around with empty transactions. Signed-off-by: Darrick J. Wong Reviewed-by: Dave Chinner Reviewed-by: Christoph Hellwig --- fs/xfs/xfs_fsmap.c | 14 +++++--------- 1 file changed, 5 insertions(+), 9 deletions(-) (limited to 'fs/xfs/xfs_fsmap.c') diff --git a/fs/xfs/xfs_fsmap.c b/fs/xfs/xfs_fsmap.c index 9ce5e7d5bf8f..34f2b971ce43 100644 --- a/fs/xfs/xfs_fsmap.c +++ b/fs/xfs/xfs_fsmap.c @@ -904,14 +904,6 @@ xfs_getfsmap( info.fsmap_recs = fsmap_recs; info.head = head; - /* - * If fsmap runs concurrently with a scrub, the freeze can be delayed - * indefinitely as we walk the rmapbt and iterate over metadata - * buffers. Freeze quiesces the log (which waits for the buffer LRU to - * be emptied) and that won't happen while we're reading buffers. - */ - sb_start_write(mp->m_super); - /* For each device we support... */ for (i = 0; i < XFS_GETFSMAP_DEVS; i++) { /* Is this device within the range the user asked for? */ @@ -934,6 +926,11 @@ xfs_getfsmap( if (handlers[i].dev > head->fmh_keys[0].fmr_device) memset(&dkeys[0], 0, sizeof(struct xfs_fsmap)); + /* + * Grab an empty transaction so that we can use its recursive + * buffer locking abilities to detect cycles in the rmapbt + * without deadlocking. + */ error = xfs_trans_alloc_empty(mp, &tp); if (error) break; @@ -951,7 +948,6 @@ xfs_getfsmap( if (tp) xfs_trans_cancel(tp); - sb_end_write(mp->m_super); head->fmh_oflags = FMH_OF_DEV_T; return error; } -- cgit v1.2.3