gfs2: Fix fallocate chunk size

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@redhat.com>
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
diff --git a/fs/gfs2/file.c b/fs/gfs2/file.c
index 4f88e20..2edd3a9 100644
--- a/fs/gfs2/file.c
+++ b/fs/gfs2/file.c
@@ -809,7 +809,7 @@
 	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 @@
 			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);