From 1866d779d5d2abae59d304e809600ca3ca8d0071 Mon Sep 17 00:00:00 2001 From: Max Reitz Date: Wed, 9 Sep 2020 17:52:17 +0200 Subject: [PATCH] fuse: Allow fuse_fill_super_common() for submounts Submounts have their own superblock, which needs to be initialized. However, they do not have a fuse_fs_context associated with them, and the root node's attributes should be taken from the mountpoint's node. Extend fuse_fill_super_common() to work for submounts by making the @ctx parameter optional, and by adding a @submount_finode parameter. (There is a plain "unsigned" in an existing code block that is being indented by this commit. Extend it to "unsigned int" so checkpatch does not complain.) Signed-off-by: Max Reitz Signed-off-by: Miklos Szeredi --- fs/fuse/fuse_i.h | 8 ++++ fs/fuse/inode.c | 109 ++++++++++++++++++++++++++++++++++++++++++++----------- 2 files changed, 96 insertions(+), 21 deletions(-) diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h index 95b81a8..d469905 100644 --- a/fs/fuse/fuse_i.h +++ b/fs/fuse/fuse_i.h @@ -1044,6 +1044,14 @@ void fuse_send_init(struct fuse_mount *fm); */ int fuse_fill_super_common(struct super_block *sb, struct fuse_fs_context *ctx); +/* + * Fill in superblock for submounts + * @sb: partially-initialized superblock to fill in + * @parent_fi: The fuse_inode of the parent filesystem where this submount is + * mounted + */ +int fuse_fill_super_submount(struct super_block *sb, + struct fuse_inode *parent_fi); /* * Remove the mount from the connection diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c index 8b34997..da5f03f 100644 --- a/fs/fuse/inode.c +++ b/fs/fuse/inode.c @@ -126,8 +126,11 @@ static void fuse_evict_inode(struct inode *inode) if (FUSE_IS_DAX(inode)) fuse_dax_inode_cleanup(inode); - fuse_queue_forget(fc, fi->forget, fi->nodeid, fi->nlookup); - fi->forget = NULL; + if (fi->nlookup) { + fuse_queue_forget(fc, fi->forget, fi->nodeid, + fi->nlookup); + fi->forget = NULL; + } } if (S_ISREG(inode->i_mode) && !is_bad_inode(inode)) { WARN_ON(!list_empty(&fi->write_files)); @@ -1207,6 +1210,87 @@ void fuse_dev_free(struct fuse_dev *fud) } EXPORT_SYMBOL_GPL(fuse_dev_free); +static void fuse_fill_attr_from_inode(struct fuse_attr *attr, + const struct fuse_inode *fi) +{ + *attr = (struct fuse_attr){ + .ino = fi->inode.i_ino, + .size = fi->inode.i_size, + .blocks = fi->inode.i_blocks, + .atime = fi->inode.i_atime.tv_sec, + .mtime = fi->inode.i_mtime.tv_sec, + .ctime = fi->inode.i_ctime.tv_sec, + .atimensec = fi->inode.i_atime.tv_nsec, + .mtimensec = fi->inode.i_mtime.tv_nsec, + .ctimensec = fi->inode.i_ctime.tv_nsec, + .mode = fi->inode.i_mode, + .nlink = fi->inode.i_nlink, + .uid = fi->inode.i_uid.val, + .gid = fi->inode.i_gid.val, + .rdev = fi->inode.i_rdev, + .blksize = 1u << fi->inode.i_blkbits, + }; +} + +static void fuse_sb_defaults(struct super_block *sb) +{ + sb->s_magic = FUSE_SUPER_MAGIC; + sb->s_op = &fuse_super_operations; + sb->s_xattr = fuse_xattr_handlers; + sb->s_maxbytes = MAX_LFS_FILESIZE; + sb->s_time_gran = 1; + sb->s_export_op = &fuse_export_operations; + sb->s_iflags |= SB_I_IMA_UNVERIFIABLE_SIGNATURE; + if (sb->s_user_ns != &init_user_ns) + sb->s_iflags |= SB_I_UNTRUSTED_MOUNTER; + sb->s_flags &= ~(SB_NOSEC | SB_I_VERSION); + + /* + * If we are not in the initial user namespace posix + * acls must be translated. + */ + if (sb->s_user_ns != &init_user_ns) + sb->s_xattr = fuse_no_acl_xattr_handlers; +} + +int fuse_fill_super_submount(struct super_block *sb, + struct fuse_inode *parent_fi) +{ + struct fuse_mount *fm = get_fuse_mount_super(sb); + struct super_block *parent_sb = parent_fi->inode.i_sb; + struct fuse_attr root_attr; + struct inode *root; + + fuse_sb_defaults(sb); + fm->sb = sb; + + WARN_ON(sb->s_bdi != &noop_backing_dev_info); + sb->s_bdi = bdi_get(parent_sb->s_bdi); + + sb->s_xattr = parent_sb->s_xattr; + sb->s_time_gran = parent_sb->s_time_gran; + sb->s_blocksize = parent_sb->s_blocksize; + sb->s_blocksize_bits = parent_sb->s_blocksize_bits; + sb->s_subtype = kstrdup(parent_sb->s_subtype, GFP_KERNEL); + if (parent_sb->s_subtype && !sb->s_subtype) + return -ENOMEM; + + fuse_fill_attr_from_inode(&root_attr, parent_fi); + root = fuse_iget(sb, parent_fi->nodeid, 0, &root_attr, 0, 0); + /* + * This inode is just a duplicate, so it is not looked up and + * its nlookup should not be incremented. fuse_iget() does + * that, though, so undo it here. + */ + get_fuse_inode(root)->nlookup--; + sb->s_d_op = &fuse_dentry_operations; + sb->s_root = d_make_root(root); + if (!sb->s_root) + return -ENOMEM; + + return 0; +} + int fuse_fill_super_common(struct super_block *sb, struct fuse_fs_context *ctx) { struct fuse_dev *fud = NULL; @@ -1220,7 +1304,7 @@ int fuse_fill_super_common(struct super_block *sb, struct fuse_fs_context *ctx) if (sb->s_flags & SB_MANDLOCK) goto err; - sb->s_flags &= ~(SB_NOSEC | SB_I_VERSION); + fuse_sb_defaults(sb); if (ctx->is_bdev) { #ifdef CONFIG_BLOCK @@ -1235,23 +1319,6 @@ int fuse_fill_super_common(struct super_block *sb, struct fuse_fs_context *ctx) sb->s_subtype = ctx->subtype; ctx->subtype = NULL; - sb->s_magic = FUSE_SUPER_MAGIC; - sb->s_op = &fuse_super_operations; - sb->s_xattr = fuse_xattr_handlers; - sb->s_maxbytes = MAX_LFS_FILESIZE; - sb->s_time_gran = 1; - sb->s_export_op = &fuse_export_operations; - sb->s_iflags |= SB_I_IMA_UNVERIFIABLE_SIGNATURE; - if (sb->s_user_ns != &init_user_ns) - sb->s_iflags |= SB_I_UNTRUSTED_MOUNTER; - - /* - * If we are not in the initial user namespace posix - * acls must be translated. - */ - if (sb->s_user_ns != &init_user_ns) - sb->s_xattr = fuse_no_acl_xattr_handlers; - if (IS_ENABLED(CONFIG_FUSE_DAX)) { err = fuse_dax_conn_alloc(fc, ctx->dax_dev); if (err) @@ -1281,7 +1348,7 @@ int fuse_fill_super_common(struct super_block *sb, struct fuse_fs_context *ctx) fc->user_id = ctx->user_id; fc->group_id = ctx->group_id; fc->legacy_opts_show = ctx->legacy_opts_show; - fc->max_read = max_t(unsigned, 4096, ctx->max_read); + fc->max_read = max_t(unsigned int, 4096, ctx->max_read); fc->destroy = ctx->destroy; fc->no_control = ctx->no_control; fc->no_force_umount = ctx->no_force_umount; -- 2.7.4