Hi,
This is a small I/O performance enhancement to gfs2. (Actually, it is a rework
of
an earlier version I got wrong). The idea here is to check if the write extends
past the last block in the file. If so, the function can save itself a lot of
time and trouble because it knows an allocate will be required. Benchmarks like
iozone should see better performance.
Regards,
Bob Peterson
Red Hat GFS
Signed-off-by: Bob Peterson <[EMAIL PROTECTED]>
--
fs/gfs2/bmap.c | 5 +++++
1 files changed, 5 insertions(+), 0 deletions(-)
diff --git a/fs/gfs2/bmap.c b/fs/gfs2/bmap.c
index 73dfad7..4356cc2 100644
--- a/fs/gfs2/bmap.c
+++ b/fs/gfs2/bmap.c
@@ -1224,6 +1224,11 @@ int gfs2_write_alloc_required(struct gfs2_inode *ip, u64
offset,
unsigned int shift = sdp->sd_sb.sb_bsize_shift;
lblock = offset >> shift;
lblock_stop = (offset + len + sdp->sd_sb.sb_bsize - 1) >> shift;
+ if (lblock_stop > ip->i_di.di_blocks) { /* writing past the
+ last block */
+ *alloc_required = 1;
+ return 0;
+ }
}
for (; lblock < lblock_stop; lblock += extlen) {
