linux-kernel - [PATCH 4.16 196/272] gfs2: Fix fallocate chunk size

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Message-Id: <20180528100257.076003397@linuxfoundation.org>
Date:   Mon, 28 May 2018 12:03:49 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Andreas Gruenbacher <agruenba@...hat.com>,
        Bob Peterson <rpeterso@...hat.com>,
        Sasha Levin <alexander.levin@...rosoft.com>
Subject: [PATCH 4.16 196/272] gfs2: Fix fallocate chunk size

4.16-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Andreas Gruenbacher <agruenba@...hat.com>

[ Upstream commit 174d1232ebc84fcde8f5889d1171c9c7e74a10a7 ]

The chunk size of allocations in __gfs2_fallocate is calculated
incorrectly.  The size can collapse, causing __gfs2_fallocate to
allocate one block at a time, which is very inefficient.  This needs
fixing in two places:

In gfs2_quota_lock_check, always set ap->allowed to UINT_MAX to indicate
that there is no quota limit.  This fixes callers that rely on
ap->allowed to be set even when quotas are off.

In __gfs2_fallocate, reset max_blks to UINT_MAX in each iteration of the
loop to make sure that allocation limits from one resource group won't
spill over into another resource group.

Signed-off-by: Andreas Gruenbacher <agruenba@...hat.com>
Signed-off-by: Bob Peterson <rpeterso@...hat.com>
Signed-off-by: Sasha Levin <alexander.levin@...rosoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 fs/gfs2/file.c  |    5 +++--
 fs/gfs2/quota.h |    2 ++
 2 files changed, 5 insertions(+), 2 deletions(-)

--- a/fs/gfs2/file.c
+++ b/fs/gfs2/file.c
@@ -809,7 +809,7 @@ static long __gfs2_fallocate(struct file
 	struct gfs2_inode *ip = GFS2_I(inode);
 	struct gfs2_alloc_parms ap = { .aflags = 0, };
 	unsigned int data_blocks = 0, ind_blocks = 0, rblocks;
-	loff_t bytes, max_bytes, max_blks = UINT_MAX;
+	loff_t bytes, max_bytes, max_blks;
 	int error;
 	const loff_t pos = offset;
 	const loff_t count = len;
@@ -861,7 +861,8 @@ static long __gfs2_fallocate(struct file
 			return error;
 		/* ap.allowed tells us how many blocks quota will allow
 		 * us to write. Check if this reduces max_blks */
-		if (ap.allowed && ap.allowed < max_blks)
+		max_blks = UINT_MAX;
+		if (ap.allowed)
 			max_blks = ap.allowed;
 
 		error = gfs2_inplace_reserve(ip, &ap);
--- a/fs/gfs2/quota.h
+++ b/fs/gfs2/quota.h
@@ -45,6 +45,8 @@ static inline int gfs2_quota_lock_check(
 {
 	struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
 	int ret;
+
+	ap->allowed = UINT_MAX; /* Assume we are permitted a whole lot */
 	if (sdp->sd_args.ar_quota == GFS2_QUOTA_OFF)
 		return 0;
 	ret = gfs2_quota_lock(ip, NO_UID_QUOTA_CHANGE, NO_GID_QUOTA_CHANGE);