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author | Al Viro <viro@zeniv.linux.org.uk> | 2020-01-17 22:04:43 -0500 |
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committer | Al Viro <viro@zeniv.linux.org.uk> | 2020-03-13 20:59:49 -0400 |
commit | b023e1728bec6dbf0c6a7e2145e2cd025c89cd55 (patch) | |
tree | 2c10e5cf35974df5e1bf368ce53635e7dc0973bf /fs/namei.c | |
parent | db3c9ade50b1f210c750886c23ba40dbf44b2bc8 (diff) | |
download | linux-b023e1728bec6dbf0c6a7e2145e2cd025c89cd55.tar.bz2 |
lookup_fast(): consolidate the RCU success case
1) in case of __follow_mount_rcu() failure, lookup_fast() proceeds
to call unlazy_child() and, should it succeed, handle_mounts().
Note that we have status > 0 (or we wouldn't be calling
__follow_mount_rcu() at all), so all stuff conditional upon
non-positive status won't be even touched.
Consolidate just that sequence after the call of __follow_mount_rcu().
2) calling d_is_negative() and keeping its result is pointless -
we either don't get past checking ->d_seq (and don't use the results of
d_is_negative() at all), or we are guaranteed that ->d_inode and
type bits of ->d_flags had been consistent at the time of d_is_negative()
call. IOW, we could only get to the use of its result if it's
equal to !inode. The same ->d_seq check guarantees that after that point
this CPU won't observe ->d_flags values older than ->d_inode update.
So 'negative' variable is completely pointless these days.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'fs/namei.c')
-rw-r--r-- | fs/namei.c | 7 |
1 files changed, 4 insertions, 3 deletions
diff --git a/fs/namei.c b/fs/namei.c index a613fa52a174..c34c27025cf0 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -1631,7 +1631,6 @@ static int lookup_fast(struct nameidata *nd, */ if (nd->flags & LOOKUP_RCU) { unsigned seq; - bool negative; dentry = __d_lookup_rcu(parent, &nd->last, &seq); if (unlikely(!dentry)) { if (unlazy_walk(nd)) @@ -1644,7 +1643,6 @@ static int lookup_fast(struct nameidata *nd, * the dentry name information from lookup. */ *inode = d_backing_inode(dentry); - negative = d_is_negative(dentry); if (unlikely(read_seqcount_retry(&dentry->d_seq, seq))) return -ECHILD; @@ -1665,12 +1663,15 @@ static int lookup_fast(struct nameidata *nd, * Note: do negative dentry check after revalidation in * case that drops it. */ - if (unlikely(negative)) + if (unlikely(!*inode)) return -ENOENT; path->mnt = mnt; path->dentry = dentry; if (likely(__follow_mount_rcu(nd, path, inode, seqp))) return 1; + if (unlazy_child(nd, dentry, seq)) + return -ECHILD; + return handle_mounts(nd, dentry, path, inode, seqp); } if (unlazy_child(nd, dentry, seq)) return -ECHILD; |