diff mbox series

[6.1,CANDIDATE,24/24] xfs: short circuit xfs_growfs_data_private() if delta is zero

Message ID 20240426215512.2673806-25-leah.rumancik@gmail.com (mailing list archive)
State Superseded, archived
Headers show
Series more backport proposals for linux-6.1.y | expand

Commit Message

Leah Rumancik April 26, 2024, 9:55 p.m. UTC 
From: Eric Sandeen <sandeen@redhat.com>

[ Upstream commit 84712492e6dab803bf595fb8494d11098b74a652 ]

Although xfs_growfs_data() doesn't call xfs_growfs_data_private()
if in->newblocks == mp->m_sb.sb_dblocks, xfs_growfs_data_private()
further massages the new block count so that we don't i.e. try
to create a too-small new AG.

This may lead to a delta of "0" in xfs_growfs_data_private(), so
we end up in the shrink case and emit the EXPERIMENTAL warning
even if we're not changing anything at all.

Fix this by returning straightaway if the block delta is zero.

(nb: in older kernels, the result of entering the shrink case
with delta == 0 may actually let an -ENOSPC escape to userspace,
which is confusing for users.)

Fixes: fb2fc1720185 ("xfs: support shrinking unused space in the last AG")
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Signed-off-by: Chandan Babu R <chandanbabu@kernel.org>
Signed-off-by: Leah Rumancik <leah.rumancik@gmail.com>
---
 fs/xfs/xfs_fsops.c | 4 ++++
 1 file changed, 4 insertions(+)
diff mbox series

Patch

diff --git a/fs/xfs/xfs_fsops.c b/fs/xfs/xfs_fsops.c
index 13851c0d640b..332da0d7b85c 100644
--- a/fs/xfs/xfs_fsops.c
+++ b/fs/xfs/xfs_fsops.c
@@ -129,6 +129,10 @@  xfs_growfs_data_private(
 	if (delta < 0 && nagcount < 2)
 		return -EINVAL;
 
+	/* No work to do */
+	if (delta == 0)
+		return 0;
+
 	oagcount = mp->m_sb.sb_agcount;
 	/* allocate the new per-ag structures */
 	if (nagcount > oagcount) {