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 <>
Signed-off-by: default avatarSteven Whitehouse <>
parent 598278bd
......@@ -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) {
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