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fix EOPENSTALE bug in do_last() 

EOPENSTALE occuring at the last component of a trailing symlink ends up
with do_last() retrying its lookup.  After the symlink body has been
discarded.  The thing is, all this retry_lookup logics in there is not
needed at all - the upper layers will do the right thing if we simply
return that -EOPENSTALE as we would with any other error.  Trying to
microoptimize in do_last() is a lot of headache for no good reason.

Cc: stable@vger.kernel.org # v4.2+
Tested-by: Oleg Drokin <green@linuxhacker.ru>
Reviewed-and-Tested-by: Jeff Layton <jlayton@poochiereds.net>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2016-06-04 11:41:49 -04:00
parent 1a695a905c
commit fac7d1917d
1 changed files with 4 additions and 39 deletions
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43
fs/namei.c
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@ -3166,9 +3166,7 @@ static int do_last(struct nameidata *nd,
int acc_mode = op->acc_mode;
unsigned seq;
struct inode *inode;
struct path save_parent = { .dentry = NULL, .mnt = NULL };
struct path path;
bool retried = false;
int error;
nd->flags &= ~LOOKUP_PARENT;
@ -3211,7 +3209,6 @@ static int do_last(struct nameidata *nd,
return -EISDIR;
}
retry_lookup:
if (open_flag & (O_CREAT | O_TRUNC | O_WRONLY | O_RDWR)) {
error = mnt_want_write(nd->path.mnt);
if (!error)
@ -3292,23 +3289,14 @@ static int do_last(struct nameidata *nd,
if (unlikely(error))
return error;
if ((nd->flags & LOOKUP_RCU) || nd->path.mnt != path.mnt) {
path_to_nameidata(&path, nd);
} else {
save_parent.dentry = nd->path.dentry;
save_parent.mnt = mntget(path.mnt);
nd->path.dentry = path.dentry;
}
path_to_nameidata(&path, nd);
nd->inode = inode;
nd->seq = seq;
/* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */
finish_open:
error = complete_walk(nd);
if (error) {
path_put(&save_parent);
if (error)
return error;
}
audit_inode(nd->name, nd->path.dentry, 0);
error = -EISDIR;
if ((open_flag & O_CREAT) && d_is_dir(nd->path.dentry))
@ -3331,13 +3319,9 @@ static int do_last(struct nameidata *nd,
goto out;
BUG_ON(*opened & FILE_OPENED); /* once it's opened, it's opened */
error = vfs_open(&nd->path, file, current_cred());
if (!error) {
*opened |= FILE_OPENED;
} else {
if (error == -EOPENSTALE)
goto stale_open;
if (error)
goto out;
}
*opened |= FILE_OPENED;
opened:
error = open_check_o_direct(file);
if (!error)
@ -3353,26 +3337,7 @@ static int do_last(struct nameidata *nd,
}
if (got_write)
mnt_drop_write(nd->path.mnt);
path_put(&save_parent);
return error;
stale_open:
/* If no saved parent or already retried then can't retry */
if (!save_parent.dentry || retried)
goto out;
BUG_ON(save_parent.dentry != dir);
path_put(&nd->path);
nd->path = save_parent;
nd->inode = dir->d_inode;
save_parent.mnt = NULL;
save_parent.dentry = NULL;
if (got_write) {
mnt_drop_write(nd->path.mnt);
got_write = false;
}
retried = true;
goto retry_lookup;
}
static int do_tmpfile(struct nameidata *nd, unsigned flags,