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Message-Id: <20200421135741.30657-3-eesposit@redhat.com>
Date: Tue, 21 Apr 2020 15:57:39 +0200
From: Emanuele Giuseppe Esposito <eesposit@...hat.com>
To: linux-fsdevel@...r.kernel.org
Cc: Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
Maxime Ripard <mripard@...nel.org>,
Thomas Zimmermann <tzimmermann@...e.de>,
David Airlie <airlied@...ux.ie>,
Daniel Vetter <daniel@...ll.ch>,
Frederic Barrat <fbarrat@...ux.ibm.com>,
Andrew Donnellan <ajd@...ux.ibm.com>,
Arnd Bergmann <arnd@...db.de>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
"Manoj N. Kumar" <manoj@...ux.ibm.com>,
"Matthew R. Ochs" <mrochs@...ux.ibm.com>,
Uma Krishnan <ukrishn@...ux.ibm.com>,
"James E.J. Bottomley" <jejb@...ux.ibm.com>,
"Martin K. Petersen" <martin.petersen@...cle.com>,
Alexander Viro <viro@...iv.linux.org.uk>,
Joel Becker <jlbec@...lplan.org>,
Christoph Hellwig <hch@....de>,
"Rafael J. Wysocki" <rafael@...nel.org>,
John Johansen <john.johansen@...onical.com>,
James Morris <jmorris@...ei.org>,
"Serge E. Hallyn" <serge@...lyn.com>,
dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
linuxppc-dev@...ts.ozlabs.org, linux-scsi@...r.kernel.org,
linux-security-module@...r.kernel.org,
Paolo Bonzini <pbonzini@...hat.com>,
Emanuele Giuseppe Esposito <eesposit@...hat.com>
Subject: [PATCH v2 5/7] libfs: add file creation functions
A bunch of code is duplicated between debugfs and tracefs, unify it to the
libfs library.
The code is very similar, except that dentry and inode creation are unified
into a single function (unlike start_creating in debugfs and tracefs, which
only takes care of dentries). This adds an output parameter to the
creation functions, but pushes all error recovery into fs/libfs.c.
Signed-off-by: Emanuele Giuseppe Esposito <eesposit@...hat.com>
---
fs/libfs.c | 226 +++++++++++++++++++++++++++++++++++++++++++++
include/linux/fs.h | 18 ++++
2 files changed, 244 insertions(+)
diff --git a/fs/libfs.c b/fs/libfs.c
index 5c76e4c648dc..90b0c221d9a2 100644
--- a/fs/libfs.c
+++ b/fs/libfs.c
@@ -751,6 +751,232 @@ struct inode *simple_alloc_anon_inode(struct simple_fs *fs)
}
EXPORT_SYMBOL(simple_alloc_anon_inode);
+static struct dentry *failed_creating(struct simple_fs *fs, struct dentry *dentry)
+{
+ inode_unlock(d_inode(dentry->d_parent));
+ dput(dentry);
+ simple_release_fs(fs);
+ return ERR_PTR(-ENOMEM);
+}
+
+/**
+ * simplefs_create_dentry - creates a new dentry and inode
+ * @fs: a pointer to a struct simple_fs containing the reference counter
+ * and vfs_mount pointer
+ * @type: the fs type
+ * @name: dentry name
+ * @parent: parent dentry. If this parameter is NULL,
+ * then the dentry will be created in the root of the
+ * filesystem.
+ * @inode: pointer that will contain a newly created inode
+ *
+ * This function returns a new dentry, or NULL on error. On success, a
+ * new inode is created and stored into @inode. Also note that the inode
+ * for the parent directory is locked by simplefs_create_dentry(),
+ * and will be unlocked by simple_finish_dentry().
+ **/
+struct dentry *simplefs_create_dentry(struct simple_fs *fs, struct file_system_type *type,
+ const char *name, struct dentry *parent,
+ struct inode **inode)
+{
+ struct dentry *dentry;
+ int error;
+
+ pr_debug("creating file '%s'\n", name);
+
+ if (IS_ERR(parent))
+ return parent;
+
+ error = simple_pin_fs(fs, type);
+ if (error) {
+ pr_err("Unable to pin filesystem for file '%s'\n", name);
+ return ERR_PTR(error);
+ }
+
+ /* If the parent is not specified, we create it in the root.
+ * We need the root dentry to do this, which is in the super
+ * block. A pointer to that is in the struct vfsmount that we
+ * have around.
+ */
+ if (!parent)
+ parent = fs->mount->mnt_root;
+
+ inode_lock(d_inode(parent));
+ dentry = lookup_one_len(name, parent, strlen(name));
+ if (!IS_ERR(dentry) && d_really_is_positive(dentry)) {
+ if (d_is_dir(dentry))
+ pr_err("Directory '%s' with parent '%s' already present!\n",
+ name, parent->d_name.name);
+ else
+ pr_err("File '%s' in directory '%s' already present!\n",
+ name, parent->d_name.name);
+ dput(dentry);
+ dentry = ERR_PTR(-EEXIST);
+ }
+
+ if (IS_ERR(dentry)) {
+ inode_unlock(d_inode(parent));
+ simple_release_fs(fs);
+ }
+
+
+ if (IS_ERR(dentry))
+ return dentry;
+
+ *inode = new_inode_current_time(fs->mount->mnt_sb);
+ if (unlikely(!(*inode))) {
+ pr_err("out of free inodes, can not create file '%s'\n",
+ name);
+ return failed_creating(fs, dentry);
+ }
+
+ return dentry;
+}
+EXPORT_SYMBOL(simplefs_create_dentry);
+
+/**
+ * simplefs_create_file - creates a new file dentry and inode
+ * @fs: a pointer to a struct simple_fs containing the reference counter
+ * and vfs_mount pointer
+ * @type: the fs type
+ * @name: file name
+ * @mode: file mode
+ * @parent: parent dentry. If this parameter is NULL,
+ * then the file will be created in the root of the
+ * filesystem.
+ * @data: what will the file contain
+ * @inode: pointer that will contain a newly created inode
+ *
+ * This function returns a new dentry, or NULL on error. On success, a
+ * new inode is created and stored into @inode. Also note that the inode
+ * for the parent directory is locked by simplefs_create_dentry(),
+ * and will be unlocked by simple_finish_dentry().
+ **/
+struct dentry *simplefs_create_file(struct simple_fs *fs, struct file_system_type *type,
+ const char *name, umode_t mode,
+ struct dentry *parent, void *data,
+ struct inode **inode)
+{
+ struct dentry *dentry;
+
+ WARN_ON((mode & S_IFMT) && !S_ISREG(mode));
+ mode |= S_IFREG;
+
+ dentry = simplefs_create_dentry(fs, type, name, parent, inode);
+
+ if (IS_ERR(dentry))
+ return dentry;
+
+ (*inode)->i_mode = mode;
+ (*inode)->i_private = data;
+
+ return dentry;
+}
+EXPORT_SYMBOL(simplefs_create_file);
+
+
+/**
+ * simplefs_finish_dentry- complete creation of a new dentry
+ * @dentry: the dentry being created
+ * @inode: the inode associated to the dentry
+ *
+ * This function completes the creation of a dentry.
+ * This includes associating @inode with the dentry, ensuring the link
+ * counts are consistent and informing fsnotify.
+ **/
+struct dentry *simplefs_finish_dentry(struct dentry *dentry, struct inode *inode)
+{
+ d_instantiate(dentry, inode);
+ if (S_ISDIR(inode->i_mode)) {
+ inc_nlink(d_inode(dentry->d_parent));
+ fsnotify_mkdir(d_inode(dentry->d_parent), dentry);
+ } else {
+ fsnotify_create(d_inode(dentry->d_parent), dentry);
+ }
+ inode_unlock(d_inode(dentry->d_parent));
+ return dentry;
+}
+EXPORT_SYMBOL(simplefs_finish_dentry);
+
+/**
+ * simplefs_create_dir - creates a new directory dentry and inode
+ * @fs: a pointer to a struct simple_fs containing the reference counter
+ * and vfs_mount pointer
+ * @type: the fs type
+ * @name: dir name
+ * @mode: dir mode
+ * @parent: parent dentry. If this parameter is NULL,
+ * then the directory will be created in the root of the
+ * filesystem.
+ * @inode: pointer that will contain a newly created inode
+ *
+ * This function returns a new dentry, or NULL on error. On success, a
+ * new inode is created and stored into @inode. Also note that the inode
+ * for the parent directory is locked by simplefs_create_dentry(),
+ * and will be unlocked by simple_finish_dentry().
+ **/
+struct dentry *simplefs_create_dir(struct simple_fs *fs, struct file_system_type *type,
+ const char *name, umode_t mode, struct dentry *parent,
+ struct inode **inode)
+{
+ struct dentry *dentry;
+
+ WARN_ON((mode & S_IFMT) && !S_ISDIR(mode));
+ mode |= S_IFDIR;
+
+ dentry = simplefs_create_dentry(fs, type, name, parent, inode);
+ if (IS_ERR(dentry))
+ return dentry;
+
+ (*inode)->i_mode = mode;
+ (*inode)->i_op = &simple_dir_inode_operations;
+ (*inode)->i_fop = &simple_dir_operations;
+
+ /* directory inodes start off with i_nlink == 2 (for "." entry) */
+ inc_nlink(*inode);
+ return dentry;
+}
+EXPORT_SYMBOL(simplefs_create_dir);
+
+/**
+ * simplefs_create_symlink - creates a new symlink dentry and inode
+ * @fs: a pointer to a struct simple_fs containing the reference counter
+ * and vfs_mount pointer
+ * @type: the fs type
+ * @name: symlink name
+ * @parent: parent dentry. If this parameter is NULL,
+ * then the symbolic link will be created in the root of the
+ * filesystem.
+ * @inode: pointer that will contain a newly created inode
+ *
+ * This function returns a new dentry, or NULL on error. On success, a
+ * new inode is created and stored into @inode. Also note that the inode
+ * for the parent directory is locked by simplefs_create_dentry(),
+ * and will be unlocked by simple_finish_dentry().
+ **/
+struct dentry *simplefs_create_symlink(struct simple_fs *fs, struct file_system_type *type,
+ const char *name, struct dentry *parent,
+ const char *target, struct inode **inode)
+{
+ struct dentry *dentry;
+ char *link = kstrdup(target, GFP_KERNEL);
+
+ if (!link)
+ return ERR_PTR(-ENOMEM);
+
+ dentry = simplefs_create_dentry(fs, type, name, parent, inode);
+ if (IS_ERR(dentry)) {
+ kfree_link(link);
+ return dentry;
+ }
+
+ (*inode)->i_mode = S_IFLNK | S_IRWXUGO;
+ (*inode)->i_link = link;
+ (*inode)->i_op = &simple_symlink_inode_operations;
+ return dentry;
+}
+EXPORT_SYMBOL(simplefs_create_symlink);
+
/**
* simple_read_from_buffer - copy data from the buffer to user space
* @to: the user space buffer to read to
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 5e93de72118b..0569540fbe61 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -3375,6 +3375,24 @@ extern void simple_release_fs(struct simple_fs *);
extern struct inode *simple_alloc_anon_inode(struct simple_fs *fs);
+extern struct dentry *simplefs_create_dentry(struct simple_fs *fs,
+ struct file_system_type *type,
+ const char *name, struct dentry *parent,
+ struct inode **inode);
+struct dentry *simplefs_finish_dentry(struct dentry *dentry, struct inode *inode);
+
+extern struct dentry *simplefs_create_file(struct simple_fs *fs,
+ struct file_system_type *type,
+ const char *name, umode_t mode,
+ struct dentry *parent, void *data,
+ struct inode **inode);
+extern struct dentry *simplefs_create_dir(struct simple_fs *fs, struct file_system_type *type,
+ const char *name, umode_t mode, struct dentry *parent,
+ struct inode **inode);
+extern struct dentry *simplefs_create_symlink(struct simple_fs *fs, struct file_system_type *type,
+ const char *name, struct dentry *parent,
+ const char *target, struct inode **inode);
+
extern ssize_t simple_read_from_buffer(void __user *to, size_t count,
loff_t *ppos, const void *from, size_t available);
extern ssize_t simple_write_to_buffer(void *to, size_t available, loff_t *ppos,
--
2.25.2
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