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lookup_fast(): don't bother with inode

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Note that validation of ->d_seq after ->d_inode fetch is gone, along
with fetching of ->d_inode itself.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2022-07-03 22:20:20 -04:00
parent b16c001de0
commit 4cb6402480
1 changed files with 4 additions and 18 deletions
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22
fs/namei.c
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@ -1621,8 +1621,7 @@ static struct dentry *__lookup_hash(const struct qstr *name,
return dentry;
}
static struct dentry *lookup_fast(struct nameidata *nd,
struct inode **inode)
static struct dentry *lookup_fast(struct nameidata *nd)
{
struct dentry *dentry, *parent = nd->path.dentry;
int status = 1;
@ -1640,22 +1639,11 @@ static struct dentry *lookup_fast(struct nameidata *nd,
return NULL;
}
/*
* This sequence count validates that the inode matches
* the dentry name information from lookup.
*/
*inode = d_backing_inode(dentry);
if (read_seqcount_retry(&dentry->d_seq, nd->next_seq))
return ERR_PTR(-ECHILD);
/*
* This sequence count validates that the parent had no
* changes while we did the lookup of the dentry above.
*
* The memory barrier in read_seqcount_begin of child is
* enough, we can use __read_seqcount_retry here.
*/
if (__read_seqcount_retry(&parent->d_seq, nd->seq))
if (read_seqcount_retry(&parent->d_seq, nd->seq))
return ERR_PTR(-ECHILD);
status = d_revalidate(dentry, nd->flags);
@ -1997,7 +1985,6 @@ static const char *handle_dots(struct nameidata *nd, int type)
static const char *walk_component(struct nameidata *nd, int flags)
{
struct dentry *dentry;
struct inode *inode;
/*
* "." and ".." are special - ".." especially so because it has
* to be able to know about the current root directory and
@ -2008,7 +1995,7 @@ static const char *walk_component(struct nameidata *nd, int flags)
put_link(nd);
return handle_dots(nd, nd->last_type);
}
dentry = lookup_fast(nd, &inode);
dentry = lookup_fast(nd);
if (IS_ERR(dentry))
return ERR_CAST(dentry);
if (unlikely(!dentry)) {
@ -3396,7 +3383,6 @@ static const char *open_last_lookups(struct nameidata *nd,
struct dentry *dir = nd->path.dentry;
int open_flag = op->open_flag;
bool got_write = false;
struct inode *inode;
struct dentry *dentry;
const char *res;
@ -3412,7 +3398,7 @@ static const char *open_last_lookups(struct nameidata *nd,
if (nd->last.name[nd->last.len])
nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
/* we _can_ be in RCU mode here */
dentry = lookup_fast(nd, &inode);
dentry = lookup_fast(nd);
if (IS_ERR(dentry))
return ERR_CAST(dentry);
if (likely(dentry))