diff options
author | Jeff Layton <jlayton@redhat.com> | 2012-12-11 08:56:16 -0500 |
---|---|---|
committer | Al Viro <viro@zeniv.linux.org.uk> | 2012-12-20 13:57:04 -0500 |
commit | 582aa64a04a579d47d05e4a0ee85bf047978ef4d (patch) | |
tree | 96c742c282b0ee6787d99704687326084a744487 /fs | |
parent | 1e75529e3c6c18dc535f38454173c4f2dfa99685 (diff) |
vfs: remove unneeded permission check from path_init
When path_init is called with a valid dfd, that code checks permissions
on the open directory fd and returns an error if the check fails. This
permission check is redundant, however.
Both callers of path_init immediately call link_path_walk afterward. The
first thing that link_path_walk does for pathnames that do not consist
only of slashes is to check for exec permissions at the starting point of
the path walk. And this check in path_init() is on the path taken only
when *name != '/' && *name != '\0'.
In most cases, these checks are very quick, but when the dfd is for a
file on a NFS mount with the actimeo=0, each permission check goes
out onto the wire. The result is 2 identical ACCESS calls.
Given that these codepaths are fairly "hot", I think it makes sense to
eliminate the permission check in path_init and simply assume that the
caller will eventually check the permissions before proceeding.
Reported-by: Dave Wysochanski <dwysocha@redhat.com>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'fs')
-rw-r--r-- | fs/namei.c | 7 |
1 files changed, 1 insertions, 6 deletions
diff --git a/fs/namei.c b/fs/namei.c index 5f4cdf3ad913..e245d88b4d69 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -1903,6 +1903,7 @@ static int path_init(int dfd, const char *name, unsigned int flags, get_fs_pwd(current->fs, &nd->path); } } else { + /* Caller must check execute permissions on the starting path component */ struct fd f = fdget_raw(dfd); struct dentry *dentry; @@ -1916,12 +1917,6 @@ static int path_init(int dfd, const char *name, unsigned int flags, fdput(f); return -ENOTDIR; } - - retval = inode_permission(dentry->d_inode, MAY_EXEC); - if (retval) { - fdput(f); - return retval; - } } nd->path = f.file->f_path; |