On Fri, 23 Jun 2006 12:14:09 +0800 (WST)
Ian Kent <[email protected]> wrote:
> >
> > Also, did you consider broadening the ->d_revalidate() semantics? It
> > appears that all implementations return 0 or 1. You could teach the VFS to
> > also recognise and act upon a -ve return value, and do this trickery within
> > the autofs d_revalidate(), perhaps?
> >
>
> Yep and I've now done this.
> I think this is in fact the only way to do it.
Below is the combined patch for reviewing purposes.
Removing that __always_inline saves 30-odd bytes. I suspect that removing
it would be a performance loss in this case. But I'll make it just
`inline' because __always_inline is peculiar, and people will wonder what's
special about this function.
fs/autofs4/root.c | 38 ++++++++++++++++++++++++++--------
fs/namei.c | 49 ++++++++++++++++++++++++++++++--------------
linux/dcache.h | 0
3 files changed, 64 insertions(+), 23 deletions(-)
diff -puN fs/autofs4/root.c~autofs4-needs-to-force-fail-return-revalidate fs/autofs4/root.c
--- a/fs/autofs4/root.c~autofs4-needs-to-force-fail-return-revalidate
+++ a/fs/autofs4/root.c
@@ -137,7 +137,9 @@ static int autofs4_dir_open(struct inode
nd.flags = LOOKUP_DIRECTORY;
ret = (dentry->d_op->d_revalidate)(dentry, &nd);
- if (!ret) {
+ if (ret <= 0) {
+ if (ret < 0)
+ status = ret;
dcache_dir_close(inode, file);
goto out;
}
@@ -400,13 +402,23 @@ static int autofs4_revalidate(struct den
struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
int oz_mode = autofs4_oz_mode(sbi);
int flags = nd ? nd->flags : 0;
- int status = 0;
+ int status = 1;
/* Pending dentry */
if (autofs4_ispending(dentry)) {
- if (!oz_mode)
- status = try_to_fill_dentry(dentry, flags);
- return !status;
+ /* The daemon never causes a mount to trigger */
+ if (oz_mode)
+ return 1;
+
+ /*
+ * A zero status is success otherwise we have a
+ * negative error code.
+ */
+ status = try_to_fill_dentry(dentry, flags);
+ if (status == 0)
+ return 1;
+
+ return status;
}
/* Negative dentry.. invalidate if "old" */
@@ -421,9 +433,19 @@ static int autofs4_revalidate(struct den
DPRINTK("dentry=%p %.*s, emptydir",
dentry, dentry->d_name.len, dentry->d_name.name);
spin_unlock(&dcache_lock);
- if (!oz_mode)
- status = try_to_fill_dentry(dentry, flags);
- return !status;
+ /* The daemon never causes a mount to trigger */
+ if (oz_mode)
+ return 1;
+
+ /*
+ * A zero status is success otherwise we have a
+ * negative error code.
+ */
+ status = try_to_fill_dentry(dentry, flags);
+ if (status == 0)
+ return 1;
+
+ return status;
}
spin_unlock(&dcache_lock);
diff -puN fs/namei.c~autofs4-needs-to-force-fail-return-revalidate fs/namei.c
--- a/fs/namei.c~autofs4-needs-to-force-fail-return-revalidate
+++ a/fs/namei.c
@@ -365,6 +365,29 @@ void release_open_intent(struct nameidat
fput(nd->intent.open.file);
}
+static __always_inline struct dentry *do_revalidate(struct dentry *dentry, struct nameidata *nd)
+{
+ int status = dentry->d_op->d_revalidate(dentry, nd);
+ if (unlikely(status <= 0)) {
+ /*
+ * The dentry failed validation.
+ * If d_revalidate returned 0 attempt to invalidate
+ * the dentry otherwise d_revalidate is asking us
+ * to return a fail status.
+ */
+ if (!status) {
+ if (!d_invalidate(dentry)) {
+ dput(dentry);
+ dentry = NULL;
+ }
+ } else {
+ dput(dentry);
+ dentry = ERR_PTR(status);
+ }
+ }
+ return dentry;
+}
+
/*
* Internal lookup() using the new generic dcache.
* SMP-safe
@@ -379,12 +402,9 @@ static struct dentry * cached_lookup(str
if (!dentry)
dentry = d_lookup(parent, name);
- if (dentry && dentry->d_op && dentry->d_op->d_revalidate) {
- if (!dentry->d_op->d_revalidate(dentry, nd) && !d_invalidate(dentry)) {
- dput(dentry);
- dentry = NULL;
- }
- }
+ if (dentry && dentry->d_op && dentry->d_op->d_revalidate)
+ dentry = do_revalidate(dentry, nd);
+
return dentry;
}
@@ -477,10 +497,9 @@ static struct dentry * real_lookup(struc
*/
mutex_unlock(&dir->i_mutex);
if (result->d_op && result->d_op->d_revalidate) {
- if (!result->d_op->d_revalidate(result, nd) && !d_invalidate(result)) {
- dput(result);
+ result = do_revalidate(result, nd);
+ if (!result)
result = ERR_PTR(-ENOENT);
- }
}
return result;
}
@@ -760,12 +779,12 @@ need_lookup:
goto done;
need_revalidate:
- if (dentry->d_op->d_revalidate(dentry, nd))
- goto done;
- if (d_invalidate(dentry))
- goto done;
- dput(dentry);
- goto need_lookup;
+ dentry = do_revalidate(dentry, nd);
+ if (!dentry)
+ goto need_lookup;
+ if (IS_ERR(dentry))
+ goto fail;
+ goto done;
fail:
return PTR_ERR(dentry);
diff -puN include/linux/dcache.h~autofs4-needs-to-force-fail-return-revalidate include/linux/dcache.h
_
-
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