On Mar 14, 2008 16:08 +0300, Andrew Perepechko wrote:
> @@ -395,7 +463,10 @@ static int v2_write_dquot(struct dquot *
> {
> int type = dquot->dq_type;
> ssize_t ret;
> - struct v2_disk_dqblk ddquot, empty;
> + union v2_disk_dqblk ddquot, empty;
> + struct super_block *sb = dquot->dq_sb;
> + uint rev = sb_dqopt(sb)->info[type].u.v2_i.dqi_revision;
> + uint dqblksz = v2_dqblksz(rev);
In a few places you add new on-stack variables like "sb", but they aren't
used more than 1 or 2 times. While it makes the code a tiny bit clearer
(though not largely so for "sb" because it is only dquot->dq_sb) it does
increase the stack usage, and that is never a good idea.
> + union v2_disk_dqblk fakedquot;
>
> + memset(&fakedquot, 0, dqblksz);
> + for (i = 0; i < dqstrinblk; i++)
> + if (!DQF_GET(ddquot+i, rev, dqb_id) &&
> + memcmp(&fakedquot, ddquot+i, dqblksz))
Hmm, allocating "fakedquot" on the stack just to compare it to zero
doesn't seem like a good use of space. What about doing the memcmp()
against page_address(ZERO_PAGE(0))? It might be nice to have a permanent
mapping of ZERO_PAGE(0) like void *zero_buffer that can be used for this.
Cheers, Andreas
--
Andreas Dilger
Sr. Staff Engineer, Lustre Group
Sun Microsystems of Canada, Inc.
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