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xfs: bulkstat chunk-formatter has issues 

The loop construct has issues:
	- clustidx is completely unused, so remove it.
	- the loop tries to be smart by terminating when the
	  "freecount" tells it that all inodes are free. Just drop
	  it as in most cases we have to scan all inodes in the
	  chunk anyway.
	- move the "user buffer left" condition check to the only
	  point where we consume space int eh user buffer.
	- move the initialisation of agino out of the loop, leaving
	  just a simple loop control logic using the clusteridx.

Also, double handling of the user buffer variables leads to problems
tracking the current state - use the cursor variables directly
rather than keeping local copies and then having to update the
cursor before returning.

cc: <stable@vger.kernel.org> # 3.17
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
This commit is contained in:
Dave Chinner 2014-11-07 08:30:58 +11:00 committed by Dave Chinner
parent bf4a5af20d
commit 2b831ac6bc
1 changed files with 25 additions and 35 deletions
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60
fs/xfs/xfs_itable.c
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@ -283,59 +283,49 @@ xfs_bulkstat_ag_ichunk(
xfs_ino_t *lastino)
{
char __user **ubufp = acp->ac_ubuffer;
int ubleft = acp->ac_ubleft;
int ubelem = acp->ac_ubelem;
int chunkidx, clustidx;
int chunkidx;
int error = 0;
xfs_agino_t agino;
for (agino = irbp->ir_startino, chunkidx = clustidx = 0;
XFS_BULKSTAT_UBLEFT(ubleft) &&
irbp->ir_freecount < XFS_INODES_PER_CHUNK;
chunkidx++, clustidx++, agino++) {
int fmterror; /* bulkstat formatter result */
agino = irbp->ir_startino;
for (chunkidx = 0; chunkidx < XFS_INODES_PER_CHUNK;
chunkidx++, agino++) {
int fmterror;
int ubused;
xfs_ino_t ino = XFS_AGINO_TO_INO(mp, agno, agino);
ASSERT(chunkidx < XFS_INODES_PER_CHUNK);
/* Skip if this inode is free */
if (XFS_INOBT_MASK(chunkidx) & irbp->ir_free) {
*lastino = ino;
continue;
}
/*
* Count used inodes as free so we can tell when the
* chunk is used up.
*/
irbp->ir_freecount++;
/* Get the inode and fill in a single buffer */
ubused = statstruct_size;
error = formatter(mp, ino, *ubufp, ubleft, &ubused, &fmterror);
if (fmterror == BULKSTAT_RV_NOTHING) {
if (error && error != -ENOENT && error != -EINVAL) {
ubleft = 0;
break;
}
*lastino = ino;
continue;
}
if (fmterror == BULKSTAT_RV_GIVEUP) {
ubleft = 0;
error = formatter(mp, ino, *ubufp, acp->ac_ubleft,
&ubused, &fmterror);
if (fmterror == BULKSTAT_RV_GIVEUP ||
(error && error != -ENOENT && error != -EINVAL)) {
acp->ac_ubleft = 0;
ASSERT(error);
break;
}
if (*ubufp)
*ubufp += ubused;
ubleft -= ubused;
ubelem++;
*lastino = ino;
}
acp->ac_ubleft = ubleft;
acp->ac_ubelem = ubelem;
/* be careful not to leak error if at end of chunk */
if (fmterror == BULKSTAT_RV_NOTHING || error) {
*lastino = ino;
error = 0;
continue;
}
*ubufp += ubused;
acp->ac_ubleft -= ubused;
acp->ac_ubelem++;
*lastino = ino;
if (acp->ac_ubleft < statstruct_size)
break;
}
return error;
}