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Commit edf24abe authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Chris Mason
Browse files

btrfs: sanity mount option parsing and early mount code



Also adds lots of comments to describe what's going on here.

Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarChris Mason <chris.mason@oracle.com>
parent 306929f3
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+1 −2
Original line number Diff line number Diff line
@@ -1616,7 +1616,6 @@ int btrfs_delete_xattrs(struct btrfs_trans_handle *trans,
			struct btrfs_root *root, struct inode *inode);
/* super.c */
u64 btrfs_parse_size(char *str);
int btrfs_parse_options(char *options, struct btrfs_root *root,
			char **subvol_name);
int btrfs_parse_options(struct btrfs_root *root, char *options);
int btrfs_sync_fs(struct super_block *sb, int wait);
#endif
+4 −1
Original line number Diff line number Diff line
@@ -1266,8 +1266,11 @@ struct btrfs_root *open_ctree(struct super_block *sb,
	if (!btrfs_super_root(disk_super))
		goto fail_sb_buffer;

	btrfs_parse_options(options, tree_root, NULL);
	err = btrfs_parse_options(tree_root, options);
	if (err)
		goto fail_sb_buffer;

	err = -EINVAL;
	if (btrfs_super_num_devices(disk_super) > fs_devices->open_devices) {
		printk("Btrfs: wanted %llu devices, but found %llu\n",
		       (unsigned long long)btrfs_super_num_devices(disk_super),
+136 −105
Original line number Diff line number Diff line
@@ -108,15 +108,18 @@ u64 btrfs_parse_size(char *str)
	return res;
}

int btrfs_parse_options(char *options, struct btrfs_root *root,
			char **subvol_name)
/*
 * Regular mount options parser.  Everything that is needed only when
 * reading in a new superblock is parsed here.
 */
int btrfs_parse_options(struct btrfs_root *root, char *options)
{
	char * p;
	struct btrfs_fs_info *info = NULL;
	struct btrfs_fs_info *info = root->fs_info;
	substring_t args[MAX_OPT_ARGS];
	char *p, *num;

	if (!options)
		return 1;
		return 0;

	/*
	 * strsep changes the string, duplicate it because parse_options
@@ -126,8 +129,6 @@ int btrfs_parse_options(char *options, struct btrfs_root *root,
	if (!options)
		return -ENOMEM;

	if (root)
		info = root->fs_info;

	while ((p = strsep(&options, ",")) != NULL) {
		int token;
@@ -137,83 +138,64 @@ int btrfs_parse_options(char *options, struct btrfs_root *root,
		token = match_token(p, tokens, args);
		switch (token) {
		case Opt_degraded:
			if (info) {
				printk("btrfs: allowing degraded mounts\n");
			printk(KERN_INFO "btrfs: allowing degraded mounts\n");
			btrfs_set_opt(info->mount_opt, DEGRADED);
			}
			break;
		case Opt_subvol:
			if (subvol_name) {
				*subvol_name = match_strdup(&args[0]);
			}
			/*
			 * This one is parsed by btrfs_parse_early_options
			 * and can be happily ignored here.
			 */
			break;
		case Opt_nodatasum:
			if (info) {
				printk("btrfs: setting nodatacsum\n");
			printk(KERN_INFO "btrfs: setting nodatacsum\n");
			btrfs_set_opt(info->mount_opt, NODATASUM);
			}
			break;
		case Opt_nodatacow:
			if (info) {
				printk("btrfs: setting nodatacow\n");
			printk(KERN_INFO "btrfs: setting nodatacow\n");
			btrfs_set_opt(info->mount_opt, NODATACOW);
			btrfs_set_opt(info->mount_opt, NODATASUM);
			}
			break;
		case Opt_ssd:
			if (info) {
				printk("btrfs: use ssd allocation scheme\n");
			printk(KERN_INFO "btrfs: use ssd allocation scheme\n");
			btrfs_set_opt(info->mount_opt, SSD);
			}
			break;
		case Opt_nobarrier:
			if (info) {
				printk("btrfs: turning off barriers\n");
			printk(KERN_INFO "btrfs: turning off barriers\n");
			btrfs_set_opt(info->mount_opt, NOBARRIER);
			}
			break;
		case Opt_max_extent:
			if (info) {
				char *num = match_strdup(&args[0]);
			num = match_strdup(&args[0]);
			if (num) {
					info->max_extent =
						btrfs_parse_size(num);
				info->max_extent = btrfs_parse_size(num);
				kfree(num);

				info->max_extent = max_t(u64,
							 info->max_extent,
							 root->sectorsize);
					printk("btrfs: max_extent at %Lu\n",
					info->max_extent, root->sectorsize);
				printk(KERN_INFO "btrfs: max_extent at %llu\n",
				       info->max_extent);
			}
			}
			break;
		case Opt_max_inline:
			if (info) {
				char *num = match_strdup(&args[0]);
			num = match_strdup(&args[0]);
			if (num) {
					info->max_inline =
						btrfs_parse_size(num);
				info->max_inline = btrfs_parse_size(num);
				kfree(num);

				info->max_inline = max_t(u64,
							 info->max_inline,
							 root->sectorsize);
					printk("btrfs: max_inline at %Lu\n",
					info->max_inline, root->sectorsize);
				printk(KERN_INFO "btrfs: max_inline at %llu\n",
					info->max_inline);
			}
			}
			break;
		case Opt_alloc_start:
			if (info) {
				char *num = match_strdup(&args[0]);
			num = match_strdup(&args[0]);
			if (num) {
					info->alloc_start =
						btrfs_parse_size(num);
				info->alloc_start = btrfs_parse_size(num);
				kfree(num);
					printk("btrfs: allocations start at "
					       "%Lu\n", info->alloc_start);
				}
				printk(KERN_INFO
					"btrfs: allocations start at %llu\n",
					info->alloc_start);
			}
			break;
		default:
@@ -221,7 +203,61 @@ int btrfs_parse_options(char *options, struct btrfs_root *root,
		}
	}
	kfree(options);
	return 1;
	return 0;
}

/*
 * Parse mount options that are required early in the mount process.
 *
 * All other options will be parsed on much later in the mount process and
 * only when we need to allocate a new super block.
 */
static int btrfs_parse_early_options(const char *options,
			char **subvol_name)
{
	substring_t args[MAX_OPT_ARGS];
	char *opts, *p;
	int error = 0;

	if (!options)
		goto out;

	/*
	 * strsep changes the string, duplicate it because parse_options
	 * gets called twice
	 */
	opts = kstrdup(options, GFP_KERNEL);
	if (!opts)
		return -ENOMEM;

	while ((p = strsep(&opts, ",")) != NULL) {
		int token;
		if (!*p)
			continue;

		token = match_token(p, tokens, args);
		switch (token) {
		case Opt_subvol:
			*subvol_name = match_strdup(&args[0]);
			break;
		default:
			break;
		}
	}

	kfree(opts);
 out:
	/*
	 * If no subvolume name is specified we use the default one.  Allocate
	 * a copy of the string "default" here so that code later in the
	 * mount path doesn't care if it's the default volume or another one.
	 */
	if (!*subvol_name) {
		*subvol_name = kstrdup("default", GFP_KERNEL);
		if (!*subvol_name)
			return -ENOMEM;
	}
	return error;
}

static int btrfs_fill_super(struct super_block * sb,
@@ -328,23 +364,33 @@ static int btrfs_test_super(struct super_block *s, void *data)
	return root->fs_info->fs_devices == test_fs_devices;
}

int btrfs_get_sb_bdev(struct file_system_type *fs_type,
	int flags, const char *dev_name, void *data,
	struct vfsmount *mnt, const char *subvol)
/*
 * Find a superblock for the given device / mount point.
 *
 * Note:  This is based on get_sb_bdev from fs/super.c with a few additions
 *	  for multiple device setup.  Make sure to keep it in sync.
 */
static int btrfs_get_sb(struct file_system_type *fs_type, int flags,
		const char *dev_name, void *data, struct vfsmount *mnt)
{
	char *subvol_name = NULL;
	struct block_device *bdev = NULL;
	struct super_block *s;
	struct dentry *root;
	struct btrfs_fs_devices *fs_devices = NULL;
	int error = 0;

	error = btrfs_parse_early_options(data, &subvol_name);
	if (error)
		goto error;

	error = btrfs_scan_one_device(dev_name, flags, fs_type, &fs_devices);
	if (error)
		return error;
		goto error_free_subvol_name;

	error = btrfs_open_devices(fs_devices, flags, fs_type);
	if (error)
		return error;
		goto error_free_subvol_name;

	bdev = fs_devices->latest_bdev;
	btrfs_lock_volumes();
@@ -378,8 +424,7 @@ int btrfs_get_sb_bdev(struct file_system_type *fs_type,
		s->s_flags |= MS_ACTIVE;
	}

	if (subvol) {
		root = lookup_one_len(subvol, s->s_root, strlen(subvol));
	root = lookup_one_len(subvol_name, s->s_root, strlen(subvol_name));
	if (IS_ERR(root)) {
		up_write(&s->s_umount);
		deactivate_super(s);
@@ -393,36 +438,22 @@ int btrfs_get_sb_bdev(struct file_system_type *fs_type,
		error = -ENXIO;
		goto error;
	}
	} else {
		root = dget(s->s_root);
	}

	mnt->mnt_sb = s;
	mnt->mnt_root = root;

	kfree(subvol_name);
	return 0;

error_s:
	error = PTR_ERR(s);
error_bdev:
	btrfs_close_devices(fs_devices);
error_free_subvol_name:
	kfree(subvol_name);
error:
	return error;
}
/* end copy & paste */

static int btrfs_get_sb(struct file_system_type *fs_type,
	int flags, const char *dev_name, void *data, struct vfsmount *mnt)
{
	int ret;
	char *subvol_name = NULL;

	btrfs_parse_options((char *)data, NULL, &subvol_name);
	ret = btrfs_get_sb_bdev(fs_type, flags, dev_name, data, mnt,
			subvol_name ? subvol_name : "default");
	if (subvol_name)
		kfree(subvol_name);
	return ret;
}

static int btrfs_statfs(struct dentry *dentry, struct kstatfs *buf)
{