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path_init(): set nd->inode earlier in cwd-relative case 

that allows to kill the recheck of nd->seq on the way out in
this case, and this check on the way out is left only for
absolute pathnames.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2015-12-05 20:25:06 -05:00
parent 9e6697e26f
commit ef55d91700
1 changed files with 12 additions and 10 deletions
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22
fs/namei.c
View File

@ -2028,6 +2028,15 @@ static const char *path_init(struct nameidata *nd, unsigned flags)
path_get(&nd->root);
nd->path = nd->root;
}
nd->inode = nd->path.dentry->d_inode;
if (!(flags & LOOKUP_RCU))
return s;
if (likely(!read_seqcount_retry(&nd->path.dentry->d_seq, nd->seq)))
return s;
if (!(nd->flags & LOOKUP_ROOT))
nd->root.mnt = NULL;
rcu_read_unlock();
return ERR_PTR(-ECHILD);
} else if (nd->dfd == AT_FDCWD) {
if (flags & LOOKUP_RCU) {
struct fs_struct *fs = current->fs;
@ -2038,11 +2047,14 @@ static const char *path_init(struct nameidata *nd, unsigned flags)
do {
seq = read_seqcount_begin(&fs->seq);
nd->path = fs->pwd;
nd->inode = nd->path.dentry->d_inode;
nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq);
} while (read_seqcount_retry(&fs->seq, seq));
} else {
get_fs_pwd(current->fs, &nd->path);
nd->inode = nd->path.dentry->d_inode;
}
return s;
} else {
/* Caller must check execute permissions on the starting path component */
struct fd f = fdget_raw(nd->dfd);
@ -2072,16 +2084,6 @@ static const char *path_init(struct nameidata *nd, unsigned flags)
fdput(f);
return s;
}
nd->inode = nd->path.dentry->d_inode;
if (!(flags & LOOKUP_RCU))
return s;
if (likely(!read_seqcount_retry(&nd->path.dentry->d_seq, nd->seq)))
return s;
if (!(nd->flags & LOOKUP_ROOT))
nd->root.mnt = NULL;
rcu_read_unlock();
return ERR_PTR(-ECHILD);
}
static const char *trailing_symlink(struct nameidata *nd)