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Tue, 21 Apr 2020 06:57:49 -0700 (PDT) From: Emanuele Giuseppe Esposito To: linux-fsdevel@vger.kernel.org Subject: [PATCH v2 5/7] libfs: add file creation functions Date: Tue, 21 Apr 2020 15:57:39 +0200 Message-Id: <20200421135741.30657-3-eesposit@redhat.com> X-Mailer: git-send-email 2.25.2 In-Reply-To: <20200421135119.30007-1-eesposit@redhat.com> References: <20200421135119.30007-1-eesposit@redhat.com> MIME-Version: 1.0 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: quoted-printable X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: "Rafael J. Wysocki" , David Airlie , dri-devel@lists.freedesktop.org, Christoph Hellwig , Andrew Donnellan , Emanuele Giuseppe Esposito , linux-scsi@vger.kernel.org, James Morris , "Serge E. Hallyn" , Daniel Vetter , Arnd Bergmann , "James E.J. Bottomley" , Maarten Lankhorst , Maxime Ripard , "Manoj N. Kumar" , Alexander Viro , "Matthew R. Ochs" , Uma Krishnan , John Johansen , "Martin K. Petersen" , Greg Kroah-Hartman , linux-kernel@vger.kernel.org, linux-security-module@vger.kernel.org, Thomas Zimmermann , Frederic Barrat , Paolo Bonzini , linuxppc-dev@lists.ozlabs.org, Joel Becker Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" 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 --- 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_f= s *fs) } EXPORT_SYMBOL(simple_alloc_anon_inode); =20 +static struct dentry *failed_creating(struct simple_fs *fs, struct dentry = *dentry) +{ +=09inode_unlock(d_inode(dentry->d_parent)); +=09dput(dentry); +=09simple_release_fs(fs); +=09return 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_sy= stem_type *type, +=09=09=09=09 const char *name, struct dentry *parent, +=09=09=09=09 struct inode **inode) +{ +=09struct dentry *dentry; +=09int error; + +=09pr_debug("creating file '%s'\n", name); + +=09if (IS_ERR(parent)) +=09=09return parent; + +=09error =3D simple_pin_fs(fs, type); +=09if (error) { +=09=09pr_err("Unable to pin filesystem for file '%s'\n", name); +=09=09return ERR_PTR(error); +=09} + +=09/* If the parent is not specified, we create it in the root. +=09 * We need the root dentry to do this, which is in the super +=09 * block. A pointer to that is in the struct vfsmount that we +=09 * have around. +=09 */ +=09if (!parent) +=09=09parent =3D fs->mount->mnt_root; + +=09inode_lock(d_inode(parent)); +=09dentry =3D lookup_one_len(name, parent, strlen(name)); +=09if (!IS_ERR(dentry) && d_really_is_positive(dentry)) { +=09=09if (d_is_dir(dentry)) +=09=09=09pr_err("Directory '%s' with parent '%s' already present!\n", +=09=09=09 name, parent->d_name.name); +=09=09else +=09=09=09pr_err("File '%s' in directory '%s' already present!\n", +=09=09=09 name, parent->d_name.name); +=09=09dput(dentry); +=09=09dentry =3D ERR_PTR(-EEXIST); +=09} + +=09if (IS_ERR(dentry)) { +=09=09inode_unlock(d_inode(parent)); +=09=09simple_release_fs(fs); +=09} + + +=09if (IS_ERR(dentry)) +=09=09return dentry; + +=09*inode =3D new_inode_current_time(fs->mount->mnt_sb); +=09if (unlikely(!(*inode))) { +=09=09pr_err("out of free inodes, can not create file '%s'\n", +=09=09 name); +=09=09return failed_creating(fs, dentry); +=09} + +=09return 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_syst= em_type *type, +=09=09=09=09 const char *name, umode_t mode, +=09=09=09=09 struct dentry *parent, void *data, +=09=09=09=09 struct inode **inode) +{ +=09struct dentry *dentry; + +=09WARN_ON((mode & S_IFMT) && !S_ISREG(mode)); +=09mode |=3D S_IFREG; + +=09dentry =3D simplefs_create_dentry(fs, type, name, parent, inode); + +=09if (IS_ERR(dentry)) +=09=09return dentry; + +=09(*inode)->i_mode =3D mode; +=09(*inode)->i_private =3D data; + +=09return 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) +{ +=09d_instantiate(dentry, inode); +=09if (S_ISDIR(inode->i_mode)) { +=09=09inc_nlink(d_inode(dentry->d_parent)); +=09=09fsnotify_mkdir(d_inode(dentry->d_parent), dentry); +=09} else { +=09=09fsnotify_create(d_inode(dentry->d_parent), dentry); +=09} +=09inode_unlock(d_inode(dentry->d_parent)); +=09return 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_syste= m_type *type, +=09=09=09=09 const char *name, umode_t mode, struct dentry *parent, +=09=09=09=09 struct inode **inode) +{ +=09struct dentry *dentry; + +=09WARN_ON((mode & S_IFMT) && !S_ISDIR(mode)); +=09mode |=3D S_IFDIR; + +=09dentry =3D simplefs_create_dentry(fs, type, name, parent, inode); +=09if (IS_ERR(dentry)) +=09=09return dentry; + +=09(*inode)->i_mode =3D mode; +=09(*inode)->i_op =3D &simple_dir_inode_operations; +=09(*inode)->i_fop =3D &simple_dir_operations; + +=09/* directory inodes start off with i_nlink =3D=3D 2 (for "." entry) */ +=09inc_nlink(*inode); +=09return 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_s= ystem_type *type, +=09=09=09=09 const char *name, struct dentry *parent, +=09=09=09=09 const char *target, struct inode **inode) +{ +=09struct dentry *dentry; +=09char *link =3D kstrdup(target, GFP_KERNEL); + +=09if (!link) +=09=09return ERR_PTR(-ENOMEM); + +=09dentry =3D simplefs_create_dentry(fs, type, name, parent, inode); +=09if (IS_ERR(dentry)) { +=09=09kfree_link(link); +=09=09return dentry; +=09} + +=09(*inode)->i_mode =3D S_IFLNK | S_IRWXUGO; +=09(*inode)->i_link =3D link; +=09(*inode)->i_op =3D &simple_symlink_inode_operations; +=09return 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 *); =20 extern struct inode *simple_alloc_anon_inode(struct simple_fs *fs); =20 +extern struct dentry *simplefs_create_dentry(struct simple_fs *fs, +=09=09=09=09=09 struct file_system_type *type, +=09=09=09=09=09 const char *name, struct dentry *parent, +=09=09=09=09=09 struct inode **inode); +struct dentry *simplefs_finish_dentry(struct dentry *dentry, struct inode = *inode); + +extern struct dentry *simplefs_create_file(struct simple_fs *fs, +=09=09=09=09=09 struct file_system_type *type, +=09=09=09=09=09 const char *name, umode_t mode, +=09=09=09=09=09 struct dentry *parent, void *data, +=09=09=09=09=09 struct inode **inode); +extern struct dentry *simplefs_create_dir(struct simple_fs *fs, struct fil= e_system_type *type, +=09=09=09=09=09 const char *name, umode_t mode, struct dentry *parent, +=09=09=09=09=09 struct inode **inode); +extern struct dentry *simplefs_create_symlink(struct simple_fs *fs, struct= file_system_type *type, +=09=09=09=09=09 const char *name, struct dentry *parent, +=09=09=09=09=09 const char *target, struct inode **inode); + extern ssize_t simple_read_from_buffer(void __user *to, size_t count, =09=09=09loff_t *ppos, const void *from, size_t available); extern ssize_t simple_write_to_buffer(void *to, size_t available, loff_t *= ppos, --=20 2.25.2