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-rw-r--r--fs/namei.c127
1 files changed, 78 insertions, 49 deletions
diff --git a/fs/namei.c b/fs/namei.c
index 3ca34388eda3..a129bc7129a1 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -4336,50 +4336,78 @@ static int may_o_create(struct mnt_idmap *idmap,
return security_inode_create(dir->dentry->d_inode, dentry, mode);
}
-/*
- * Attempt to atomically look up, create and open a file from a negative
- * dentry.
- *
- * Returns 0 if successful. The file will have been created and attached to
- * @file by the filesystem calling finish_open().
- *
- * If the file was looked up only or didn't need creating, FMODE_OPENED won't
- * be set. The caller will need to perform the open themselves. @path will
- * have been updated to point to the new dentry. This may be negative.
- *
- * Returns an error code otherwise.
+/**
+ * atomic_open() - attempt to atomically look up, create and open a file
+ * from a negative dentry.
+ * @path: parent directory path
+ * @dentry: child to ->atomic_open()
+ * @file: file to attach child to
+ * @open_flag: open flags
+ * @mode: create mode
+ * @create_error: return value from may_o_create()
+ *
+ * If a non-error dentry is returned then: when FMODE_OPENED is set,
+ * the file will have been attached to @file by the filesystem calling
+ * finish_open(). If FMODE_OPENED isn't set, the filesystem instead called
+ * finish_no_open() and the caller will need to perform the open themselves.
+ *
+ * FMODE_CREATED is set when the call to ->atomic_open() actually created
+ * the file.
+ *
+ * Returns the opened/looked-up dentry on success or ERR_PTR(-E) on failure.
+ * On error, atomic_open() consumes @dentry.
*/
static struct dentry *atomic_open(const struct path *path, struct dentry *dentry,
struct file *file,
- int open_flag, umode_t mode)
+ int open_flag, umode_t mode, int create_error)
{
struct dentry *const DENTRY_NOT_SET = (void *) -1UL;
- struct inode *dir = path->dentry->d_inode;
+ struct inode *dir_inode = path->dentry->d_inode;
int error;
file->__f_path.dentry = DENTRY_NOT_SET;
file->__f_path.mnt = path->mnt;
- error = dir->i_op->atomic_open(dir, dentry, file,
+ error = dir_inode->i_op->atomic_open(dir_inode, dentry, file,
open_to_namei_flags(open_flag), mode);
d_lookup_done(dentry);
+
if (!error) {
if (file->f_mode & FMODE_OPENED) {
- if (unlikely(dentry != file->f_path.dentry)) {
+ /* finish_open() called */
+ struct dentry *opened = file->f_path.dentry;
+ if (unlikely(opened != dentry)) {
dput(dentry);
- dentry = dget(file->f_path.dentry);
+ dentry = dget(opened);
}
- } else if (WARN_ON(file->f_path.dentry == DENTRY_NOT_SET)) {
- error = -EIO;
- } else {
- if (file->f_path.dentry) {
+ } else if (likely(file->f_path.dentry != DENTRY_NOT_SET)) {
+ /* finish_no_open() called */
+ struct dentry *replaced = file->f_path.dentry;
+ if (replaced) {
dput(dentry);
- dentry = file->f_path.dentry;
+ dentry = replaced;
}
if (unlikely(d_is_negative(dentry)))
error = -ENOENT;
+ } else {
+ const char *fsname = dentry->d_sb->s_type->name;
+ WARN(1, "%s: ->atomic_open() left file->f_path.dentry unset!\n",
+ fsname);
+ error = -EIO;
}
}
+
if (error) {
+ if (unlikely(create_error) && error == -ENOENT) {
+ /*
+ * Should have done a create, but errored before.
+ * Some filesystems return -ENOENT directly instead of
+ * calling finish_no_open() with a negative dentry;
+ * either way it should only mean the child doesn't exist,
+ * so a refused create is safe to record here.
+ */
+ audit_inode_child(dir_inode, dentry, AUDIT_TYPE_CHILD_CREATE);
+ error = create_error;
+ }
dput(dentry);
dentry = ERR_PTR(error);
}
@@ -4459,7 +4487,7 @@ retry:
dentry = NULL;
}
if (dentry->d_inode) {
- /* Cached positive dentry: will open in f_op->open */
+ /* Cached positive dentry: will open in do_open(). */
goto out;
}
@@ -4493,9 +4521,8 @@ retry:
if (dir_inode->i_op->atomic_open) {
if (nd->flags & LOOKUP_DIRECTORY)
open_flag |= O_DIRECTORY;
- dentry = atomic_open(&nd->path, dentry, file, open_flag, mode);
- if (unlikely(create_error) && dentry == ERR_PTR(-ENOENT))
- dentry = ERR_PTR(create_error);
+ dentry = atomic_open(&nd->path, dentry, file, open_flag, mode,
+ create_error);
goto out;
}
@@ -4512,30 +4539,35 @@ retry:
dentry = res;
}
}
+ if (dentry->d_inode || !(op->open_flag & O_CREAT)) {
+ /* No need to create a file. If lookup returned a positive
+ * dentry, the file will be opened in do_open(). */
+ goto out;
+ }
- /* Negative dentry, just create the file */
- if (!dentry->d_inode && (open_flag & O_CREAT)) {
- /* but break the directory lease first! */
- error = try_break_deleg(dir_inode, LEASE_BREAK_DIR_CREATE, &delegated_inode);
- if (error)
- goto out_dput;
-
- file->f_mode |= FMODE_CREATED;
- audit_inode_child(dir_inode, dentry, AUDIT_TYPE_CHILD_CREATE);
- if (!dir_inode->i_op->create) {
- error = -EACCES;
- goto out_dput;
- }
+ /* Negative dentry with O_CREAT flag set */
+ audit_inode_child(dir_inode, dentry, AUDIT_TYPE_CHILD_CREATE);
- error = dir_inode->i_op->create(idmap, dir_inode, dentry,
- mode, open_flag & O_EXCL);
- if (error)
- goto out_dput;
- }
- if (unlikely(create_error) && !dentry->d_inode) {
+ if (unlikely(create_error)) {
+ /* should have done a create, but we already errored */
error = create_error;
goto out_dput;
}
+
+ error = try_break_deleg(dir_inode, LEASE_BREAK_DIR_CREATE, &delegated_inode);
+ if (error)
+ goto out_dput;
+
+ file->f_mode |= FMODE_CREATED;
+ if (!dir_inode->i_op->create) {
+ error = -EACCES;
+ goto out_dput;
+ }
+
+ error = dir_inode->i_op->create(idmap, dir_inode, dentry,
+ mode, open_flag & O_EXCL);
+ if (error)
+ goto out_dput;
out:
if (!IS_ERR(dentry)) {
if (file->f_mode & FMODE_CREATED)
@@ -5153,7 +5185,7 @@ struct file *dentry_create(struct path *path, int flags, umode_t mode,
/* atomic_open will dput(dentry) on error */
dget(orig_dentry);
- dentry = atomic_open(path, dentry, file, flags, mode);
+ dentry = atomic_open(path, dentry, file, flags, mode, create_error);
error = PTR_ERR_OR_ZERO(dentry);
if (IS_ERR(dentry))
@@ -5163,9 +5195,6 @@ struct file *dentry_create(struct path *path, int flags, umode_t mode,
/* Drop the extra reference */
dput(orig_dentry);
- if (unlikely(create_error) && error == -ENOENT)
- error = create_error;
-
if (!error) {
if (file->f_mode & FMODE_CREATED)
fsnotify_create(dir->d_inode, dentry);
generated by cgit v1.2.3 (git 2.0.4) at 2026-08-20 19:58:01 +0000