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authorMax Reitz <mreitz@redhat.com>2020-09-09 18:52:17 +0300
committerMiklos Szeredi <mszeredi@redhat.com>2020-09-18 16:17:41 +0300
commit1866d779d5d2abae59d304e809600ca3ca8d0071 (patch)
treef6ab5f44aeefd72c9f37e477158ba409a3c35231
parentfcee216beb9c15c3e1466bb76575358415687c55 (diff)
downloadlinux-1866d779d5d2abae59d304e809600ca3ca8d0071.tar.xz
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 <mreitz@redhat.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
-rw-r--r--fs/fuse/fuse_i.h8
-rw-r--r--fs/fuse/inode.c109
2 files changed, 96 insertions, 21 deletions
diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index 95b81a87941d..d469905166ab 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 8b34997a0eef..da5f03f910cf 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;