From: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
it's easier to drop it right after lookup_open() and regain if
needed (i.e. if we will need to truncate). On the non-FMODE_OPENED
path we do that anyway. In case of FMODE_CREATED we won't be
needing it. And it's easier to prove correctness that way,
especially since the initial failure to get write access is not
always fatal; proving that we'll never end up truncating in that
case is rather convoluted.
Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
---
fs/namei.c | 31 +++++++++++--------------------
1 file changed, 11 insertions(+), 20 deletions(-)
diff --git a/fs/namei.c b/fs/namei.c
index f79e020f08fe..56285466aa55 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -3199,11 +3199,14 @@ static const char *do_last(struct nameidata *nd,
else
inode_unlock_shared(dir->d_inode);
- if (IS_ERR(dentry)) {
- error = PTR_ERR(dentry);
- goto out;
+ if (got_write) {
+ mnt_drop_write(nd->path.mnt);
+ got_write = false;
}
+ if (IS_ERR(dentry))
+ return ERR_CAST(dentry);
+
if (file->f_mode & FMODE_OPENED) {
if (file->f_mode & FMODE_CREATED) {
open_flag &= ~O_TRUNC;
@@ -3228,16 +3231,6 @@ static const char *do_last(struct nameidata *nd,
goto finish_open_created;
}
- /*
- * If atomic_open() acquired write access it is dropped now due to
- * possible mount and symlink following (this might be optimized away if
- * necessary...)
- */
- if (got_write) {
- mnt_drop_write(nd->path.mnt);
- got_write = false;
- }
-
finish_lookup:
link = step_into(nd, 0, dentry, inode, seq);
if (unlikely(link)) {
@@ -3258,27 +3251,25 @@ static const char *do_last(struct nameidata *nd,
return ERR_PTR(error);
audit_inode(nd->name, nd->path.dentry, 0);
if (open_flag & O_CREAT) {
- error = -EISDIR;
if (d_is_dir(nd->path.dentry))
- goto out;
+ return ERR_PTR(-EISDIR);
error = may_create_in_sticky(dir_mode, dir_uid,
d_backing_inode(nd->path.dentry));
if (unlikely(error))
- goto out;
+ return ERR_PTR(error);
}
- error = -ENOTDIR;
if ((nd->flags & LOOKUP_DIRECTORY) && !d_can_lookup(nd->path.dentry))
- goto out;
+ return ERR_PTR(-ENOTDIR);
if (!d_is_reg(nd->path.dentry))
will_truncate = false;
+finish_open_created:
if (will_truncate) {
error = mnt_want_write(nd->path.mnt);
if (error)
- goto out;
+ return ERR_PTR(error);
got_write = true;
}
-finish_open_created:
error = may_open(&nd->path, acc_mode, open_flag);
if (error)
goto out;
--
2.11.0
