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

fs/btrfs/ctree.h

+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

fs/btrfs/disk-io.c

+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),

fs/btrfs/super.c

+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)

{