Re: [PATCH] XFS: remove pointless conditional testing 'nmp' vs NULL in fs/xfs/xfs_rtalloc.c::xfs_growfs_rt()

From: Jesper Juhl
Date: Wed Aug 16 2006 - 16:40:42 EST


On Monday 14 August 2006 09:25, Jesper Juhl wrote:
> On 14/08/06, Nathan Scott <nathans@xxxxxxx> wrote:
> > On Sun, Aug 13, 2006 at 12:16:50AM +0200, Jesper Juhl wrote:
> >
> > Really this code would be better if reworked slightly to just
> > allocate nmp once before entering the loop, and then free it
> > once at the end... we wouldn't need a goto, just a few breaks
> > in the loop and a conditional transaction cancel.
> >
> > > This patch gets rid of the pointless check.
> >
> > Hmm, seems like code churn that makes the code slightly less
> > obvious, but thats just me... I'd prefer a tested patch that
> > implements the above suggestion, to be honest. :)
> >
> Ok, I'll see what I can come up with.
>

How this?

Compile tested only since I'm at home and don't have any XFS filesystems to
play with atm.



Rework fs/xfs/xfs_rtalloc.c::xfs_growfs_rt() to allocate and free 'nmp' just
once and make the error handling a bit clearer.

Signed-off-by: Jesper Juhl <jesper.juhl@xxxxxxxxx>
---

fs/xfs/xfs_rtalloc.c | 37 +++++++++++++++----------------------
1 files changed, 15 insertions(+), 22 deletions(-)

--- linux-2.6.18-rc4-orig/fs/xfs/xfs_rtalloc.c 2006-08-11 00:11:13.000000000 +0200
+++ linux-2.6.18-rc4/fs/xfs/xfs_rtalloc.c 2006-08-16 22:36:03.000000000 +0200
@@ -1976,7 +1976,11 @@ xfs_growfs_rt(
if ((error = xfs_growfs_rt_alloc(mp, rsumblocks, nrsumblocks,
mp->m_sb.sb_rsumino)))
return error;
- nmp = NULL;
+
+ /*
+ * Allocate a new (fake) mount/sb.
+ */
+ nmp = kmem_alloc(sizeof(*nmp), KM_SLEEP);
/*
* Loop over the bitmap blocks.
* We will do everything one bitmap block at a time.
@@ -1987,10 +1991,6 @@ xfs_growfs_rt(
((sbp->sb_rextents & ((1 << mp->m_blkbit_log) - 1)) != 0);
bmbno < nrbmblocks;
bmbno++) {
- /*
- * Allocate a new (fake) mount/sb.
- */
- nmp = kmem_alloc(sizeof(*nmp), KM_SLEEP);
*nmp = *mp;
nsbp = &nmp->m_sb;
/*
@@ -2018,13 +2018,13 @@ xfs_growfs_rt(
cancelflags = 0;
if ((error = xfs_trans_reserve(tp, 0,
XFS_GROWRTFREE_LOG_RES(nmp), 0, 0, 0)))
- goto error_exit;
+ break;
/*
* Lock out other callers by grabbing the bitmap inode lock.
*/
if ((error = xfs_trans_iget(mp, tp, mp->m_sb.sb_rbmino, 0,
XFS_ILOCK_EXCL, &ip)))
- goto error_exit;
+ break;
ASSERT(ip == mp->m_rbmip);
/*
* Update the bitmap inode's size.
@@ -2038,7 +2038,7 @@ xfs_growfs_rt(
*/
if ((error = xfs_trans_iget(mp, tp, mp->m_sb.sb_rsumino, 0,
XFS_ILOCK_EXCL, &ip)))
- goto error_exit;
+ break;
ASSERT(ip == mp->m_rsumip);
/*
* Update the summary inode's size.
@@ -2053,7 +2053,7 @@ xfs_growfs_rt(
mp->m_rsumlevels != nmp->m_rsumlevels) {
error = xfs_rtcopy_summary(mp, nmp, tp);
if (error)
- goto error_exit;
+ break;
}
/*
* Update superblock fields.
@@ -2080,18 +2080,13 @@ xfs_growfs_rt(
error = xfs_rtfree_range(nmp, tp, sbp->sb_rextents,
nsbp->sb_rextents - sbp->sb_rextents, &bp, &sumbno);
if (error)
- goto error_exit;
+ break;
/*
* Mark more blocks free in the superblock.
*/
xfs_trans_mod_sb(tp, XFS_TRANS_SB_FREXTENTS,
nsbp->sb_rextents - sbp->sb_rextents);
/*
- * Free the fake mp structure.
- */
- kmem_free(nmp, sizeof(*nmp));
- nmp = NULL;
- /*
* Update mp values into the real mp structure.
*/
mp->m_rsumlevels = nrsumlevels;
@@ -2101,15 +2096,13 @@ xfs_growfs_rt(
*/
xfs_trans_commit(tp, 0, NULL);
}
- return 0;
-
+ if (error)
+ xfs_trans_cancel(tp, cancelflags);
/*
- * Error paths come here.
+ * Free the fake mp structure.
*/
-error_exit:
- if (nmp)
- kmem_free(nmp, sizeof(*nmp));
- xfs_trans_cancel(tp, cancelflags);
+ kmem_free(nmp, sizeof(*nmp));
+
return error;
}



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