From 05220535196d413db434527a3edcba79b7187df8 Mon Sep 17 00:00:00 2001 From: Bob Peterson Date: Fri, 11 Jan 2008 13:44:50 -0600 Subject: [PATCH] [GFS2] gfs2_alloc_required performance 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. Signed-off-by: Bob Peterson Signed-off-by: Steven Whitehouse --- fs/gfs2/bmap.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/fs/gfs2/bmap.c b/fs/gfs2/bmap.c index 73dfad70de66..4356cc2fb3f5 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) { -- 2.20.1