From 8f2918898eb5fe25845dde7f4a77bda0e2966e05 Mon Sep 17 00:00:00 2001 From: Al Viro Date: Sun, 4 Nov 2018 06:48:34 -0500 Subject: new helpers: vfs_create_mount(), fc_mount() Create a new helper, vfs_create_mount(), that creates a detached vfsmount object from an fs_context that has a superblock attached to it. Almost all uses will be paired with immediately preceding vfs_get_tree(); add a helper for such combination. Switch vfs_kern_mount() to use this. NOTE: mild behaviour change; passing NULL as 'device name' to something like procfs will change /proc/*/mountstats - "device none" instead on "no device". That is consistent with /proc/mounts et.al. [do'h - EXPORT_SYMBOL_GPL slipped in by mistake; removed] [AV -- remove confused comment from vfs_create_mount()] [AV -- removed the second argument] Reviewed-by: David Howells Signed-off-by: Al Viro --- fs/namespace.c | 76 +++++++++++++++++++++++++++++++++++++++------------------- 1 file changed, 52 insertions(+), 24 deletions(-) (limited to 'fs/namespace.c') diff --git a/fs/namespace.c b/fs/namespace.c index 3f2fd7a34733..156771f5745a 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -941,12 +941,59 @@ static struct mount *skip_mnt_tree(struct mount *p) return p; } +/** + * vfs_create_mount - Create a mount for a configured superblock + * @fc: The configuration context with the superblock attached + * + * Create a mount to an already configured superblock. If necessary, the + * caller should invoke vfs_get_tree() before calling this. + * + * Note that this does not attach the mount to anything. + */ +struct vfsmount *vfs_create_mount(struct fs_context *fc) +{ + struct mount *mnt; + + if (!fc->root) + return ERR_PTR(-EINVAL); + + mnt = alloc_vfsmnt(fc->source ?: "none"); + if (!mnt) + return ERR_PTR(-ENOMEM); + + if (fc->sb_flags & SB_KERNMOUNT) + mnt->mnt.mnt_flags = MNT_INTERNAL; + + atomic_inc(&fc->root->d_sb->s_active); + mnt->mnt.mnt_sb = fc->root->d_sb; + mnt->mnt.mnt_root = dget(fc->root); + mnt->mnt_mountpoint = mnt->mnt.mnt_root; + mnt->mnt_parent = mnt; + + lock_mount_hash(); + list_add_tail(&mnt->mnt_instance, &mnt->mnt.mnt_sb->s_mounts); + unlock_mount_hash(); + return &mnt->mnt; +} +EXPORT_SYMBOL(vfs_create_mount); + +struct vfsmount *fc_mount(struct fs_context *fc) +{ + int err = vfs_get_tree(fc); + if (!err) { + up_write(&fc->root->d_sb->s_umount); + return vfs_create_mount(fc); + } + return ERR_PTR(err); +} +EXPORT_SYMBOL(fc_mount); + struct vfsmount *vfs_kern_mount(struct file_system_type *type, int flags, const char *name, void *data) { struct fs_context *fc; - struct mount *mnt; + struct vfsmount *mnt; int ret = 0; if (!type) @@ -964,31 +1011,12 @@ struct vfsmount *vfs_kern_mount(struct file_system_type *type, if (!ret) ret = parse_monolithic_mount_data(fc, data); if (!ret) - ret = vfs_get_tree(fc); - if (ret) { - put_fs_context(fc); - return ERR_PTR(ret); - } - up_write(&fc->root->d_sb->s_umount); - mnt = alloc_vfsmnt(name); - if (!mnt) { - put_fs_context(fc); - return ERR_PTR(-ENOMEM); - } - - if (flags & SB_KERNMOUNT) - mnt->mnt.mnt_flags = MNT_INTERNAL; + mnt = fc_mount(fc); + else + mnt = ERR_PTR(ret); - atomic_inc(&fc->root->d_sb->s_active); - mnt->mnt.mnt_root = dget(fc->root); - mnt->mnt.mnt_sb = fc->root->d_sb; - mnt->mnt_mountpoint = mnt->mnt.mnt_root; - mnt->mnt_parent = mnt; - lock_mount_hash(); - list_add_tail(&mnt->mnt_instance, &fc->root->d_sb->s_mounts); - unlock_mount_hash(); put_fs_context(fc); - return &mnt->mnt; + return mnt; } EXPORT_SYMBOL_GPL(vfs_kern_mount); -- cgit