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Commit 05220535 authored by Bob Peterson's avatar Bob Peterson Committed by Steven Whitehouse
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[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: default avatarBob Peterson <rpeterso@redhat.com>
Signed-off-by: default avatarSteven Whitehouse <swhiteho@redhat.com>
parent 598278bd

fs/gfs2/bmap.c

+5 −0
Original line number Diff line number Diff line
@@ -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) {