[Cluster-devel] [PATCH v4 04/20] gfs2: Some documentation updates
Andreas Gruenbacher
agruenba at redhat.com
Wed Feb 3 18:07:39 UTC 2021
The calc_reserved description claims that buf_limit is 502 (on 4k
filesystems), but it is actually 503. Fix / clarify the entire
description.
Signed-off-by: Andreas Gruenbacher <agruenba at redhat.com>
---
fs/gfs2/log.c | 24 +++++++++++-------------
1 file changed, 11 insertions(+), 13 deletions(-)
diff --git a/fs/gfs2/log.c b/fs/gfs2/log.c
index ccce17fe605f..12e8280f0806 100644
--- a/fs/gfs2/log.c
+++ b/fs/gfs2/log.c
@@ -50,10 +50,12 @@ unsigned int gfs2_struct2blk(struct gfs2_sbd *sdp, unsigned int nstruct)
unsigned int blks;
unsigned int first, second;
+ /* The initial struct gfs2_log_descriptor block */
blks = 1;
first = sdp->sd_ldptrs;
if (nstruct > first) {
+ /* Subsequent struct gfs2_meta_header blocks */
second = sdp->sd_inptrs;
blks += DIV_ROUND_UP(nstruct - first, second);
}
@@ -507,24 +509,20 @@ static inline unsigned int log_distance(struct gfs2_sbd *sdp, unsigned int newer
}
/**
- * calc_reserved - Calculate the number of blocks to reserve when
- * refunding a transaction's unused buffers.
+ * calc_reserved - Calculate the number of blocks to keep reserved
* @sdp: The GFS2 superblock
*
* This is complex. We need to reserve room for all our currently used
- * metadata buffers (e.g. normal file I/O rewriting file time stamps) and
- * all our journaled data buffers for journaled files (e.g. files in the
+ * metadata blocks (e.g. normal file I/O rewriting file time stamps) and
+ * all our journaled data blocks for journaled files (e.g. files in the
* meta_fs like rindex, or files for which chattr +j was done.)
- * If we don't reserve enough space, gfs2_log_refund and gfs2_log_flush
- * will count it as free space (sd_log_blks_free) and corruption will follow.
+ * If we don't reserve enough space, corruption will follow.
*
- * We can have metadata bufs and jdata bufs in the same journal. So each
- * type gets its own log header, for which we need to reserve a block.
- * In fact, each type has the potential for needing more than one header
- * in cases where we have more buffers than will fit on a journal page.
+ * We can have metadata blocks and jdata blocks in the same journal. Each
+ * type gets its own log descriptor, for which we need to reserve a block.
+ * In fact, each type has the potential for needing more than one log descriptor
+ * in cases where we have more blocks than will fit in a log descriptor.
* Metadata journal entries take up half the space of journaled buffer entries.
- * Thus, metadata entries have buf_limit (502) and journaled buffers have
- * databuf_limit (251) before they cause a wrap around.
*
* Also, we need to reserve blocks for revoke journal entries and one for an
* overall header for the lot.
@@ -1008,7 +1006,7 @@ void gfs2_log_flush(struct gfs2_sbd *sdp, struct gfs2_glock *gl, u32 flags)
if (sdp->sd_log_head != sdp->sd_log_flush_head) {
log_flush_wait(sdp);
log_write_header(sdp, flags);
- } else if (sdp->sd_log_tail != current_tail(sdp) && !sdp->sd_log_idle){
+ } else if (sdp->sd_log_tail != current_tail(sdp) && !sdp->sd_log_idle) {
atomic_dec(&sdp->sd_log_blks_free); /* Adjust for unreserved buffer */
trace_gfs2_log_blocks(sdp, -1);
log_write_header(sdp, flags);
--
2.26.2
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