From: Steven Whitehouse <swhiteho@redhat.com>
Subject: [RHEL 5.1] [GFS2] Fix calculation for spare log blocks with 	smaller block sizes (bz #240435)
Date: Mon, 04 Jun 2007 11:14:41 +0100
Bugzilla: 240435
Message-Id: <1180952081.25918.147.camel@quoit>
Changelog: [GFS2] Fix calculation for spare log blocks with smaller block sizes


Hi,

This patch fixes the calculation of log blocks which are reserved when
smaller block sizes (than the 4k default) are in use. Its in the
upstream -nmw git tree and is safe because it will always result in a
larger number of blocks being reserved and thus erring on the side of
caution,

Steve.



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X-Git-Url: http://git.kernel.org/?p=linux%2Fkernel%2Fgit%2Fsteve%2Fgfs2-2.6-nmw.git;a=commitdiff_plain;h=6aada4d55551544cc8c60786f349d3700d78ed96

[GFS2] Make the log reserved blocks depend on block size

The number of blocks which we reserve in the log at the start of each
transaction needs to depends upon the block size since the overhead is
related to the number of "pointers" which can be fitted into a single
block.

This relates to Red Hat bz #240435

Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
---

diff --git a/fs/gfs2/log.c b/fs/gfs2/log.c
index 291415d..586923d 100644
--- a/fs/gfs2/log.c
+++ b/fs/gfs2/log.c
@@ -262,7 +262,7 @@ static void ail2_empty(struct gfs2_sbd *sdp, unsigned int new_tail)
  * @sdp: The GFS2 superblock
  * @blks: The number of blocks to reserve
  *
- * Note that we never give out the last 6 blocks of the journal. Thats
+ * Note that we never give out the last few blocks of the journal. Thats
  * due to the fact that there is are a small number of header blocks
  * associated with each log flush. The exact number can't be known until
  * flush time, so we ensure that we have just enough free blocks at all
@@ -274,6 +274,7 @@ static void ail2_empty(struct gfs2_sbd *sdp, unsigned int new_tail)
 int gfs2_log_reserve(struct gfs2_sbd *sdp, unsigned int blks)
 {
 	unsigned int try = 0;
+	unsigned reserved_blks = 6 * (4096 / sdp->sd_vfs->s_blocksize);
 
 	if (gfs2_assert_warn(sdp, blks) ||
 	    gfs2_assert_warn(sdp, blks <= sdp->sd_jdesc->jd_blocks))
@@ -281,7 +282,7 @@ int gfs2_log_reserve(struct gfs2_sbd *sdp, unsigned int blks)
 
 	mutex_lock(&sdp->sd_log_reserve_mutex);
 	gfs2_log_lock(sdp);
-	while(sdp->sd_log_blks_free <= (blks + 6)) {
+	while(sdp->sd_log_blks_free <= (blks + reserved_blks)) {
 		gfs2_log_unlock(sdp);
 		gfs2_ail1_empty(sdp, 0);
 		gfs2_log_flush(sdp, NULL);