From 90f414686bc48d8e7b886d059c94d2977d3601bd Mon Sep 17 00:00:00 2001 From: "Darrick J. Wong" Date: Fri, 19 Aug 2022 11:14:27 -0700 Subject: [PATCH] xfs: always succeed at setting the reserve pool size [ Upstream commit 0baa2657dc4d79202148be79a3dc36c35f425060 ] Nowadays, xfs_mod_fdblocks will always choose to fill the reserve pool with freed blocks before adding to fdblocks. Therefore, we can change the behavior of xfs_reserve_blocks slightly -- setting the target size of the pool should always succeed, since a deficiency will eventually be made up as blocks get freed. Signed-off-by: Darrick J. Wong Reviewed-by: Dave Chinner Signed-off-by: Leah Rumancik Acked-by: Darrick J. Wong Signed-off-by: Greg Kroah-Hartman --- fs/xfs/xfs_fsops.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/fs/xfs/xfs_fsops.c b/fs/xfs/xfs_fsops.c index 3c6d9d6..5c2bea1 100644 --- a/fs/xfs/xfs_fsops.c +++ b/fs/xfs/xfs_fsops.c @@ -434,11 +434,14 @@ xfs_reserve_blocks( * The code below estimates how many blocks it can request from * fdblocks to stash in the reserve pool. This is a classic TOCTOU * race since fdblocks updates are not always coordinated via - * m_sb_lock. + * m_sb_lock. Set the reserve size even if there's not enough free + * space to fill it because mod_fdblocks will refill an undersized + * reserve when it can. */ free = percpu_counter_sum(&mp->m_fdblocks) - xfs_fdblocks_unavailable(mp); delta = request - mp->m_resblks; + mp->m_resblks = request; if (delta > 0 && free > 0) { /* * We'll either succeed in getting space from the free block @@ -455,10 +458,8 @@ xfs_reserve_blocks( * Update the reserve counters if blocks have been successfully * allocated. */ - if (!error) { - mp->m_resblks += fdblks_delta; + if (!error) mp->m_resblks_avail += fdblks_delta; - } } out: if (outval) { -- 2.7.4