Christoph Hellwig
2008-Jun-10 12:34 UTC
[PATCH] btrfs: sanity mount option parsing and early mount code
- split mount option parsing into two helpers, one for the early
options (currentl only the subvol option) and one for the
later per-superblock options.
- deal with error from mount options parsing
- use proper KERN_INFO prefixes for messages from mount option
parsing
- merge btrfs_get_sb_bdev into btrfs_get_sb. It has diverged
from get_sb_bdev enough to be quite btrfs-specific so there''s
no need to keep it separate.
Also adds lots of comments to describe what''s going on here.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Index: btrfs-unstable/super.c
==================================================================---
btrfs-unstable.orig/super.c 2008-06-09 13:53:57.000000000 +0200
+++ btrfs-unstable/super.c 2008-06-10 10:40:18.000000000 +0200
@@ -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
@@ -126,10 +129,8 @@ int btrfs_parse_options(char *options, s
if (!options)
return -ENOMEM;
- if (root)
- info = root->fs_info;
- while ((p = strsep (&options, ",")) != NULL) {
+ while ((p = strsep(&options, ",")) != NULL) {
int token;
if (!*p)
continue;
@@ -137,83 +138,64 @@ int btrfs_parse_options(char *options, s
token = match_token(p, tokens, args);
switch (token) {
case Opt_degraded:
- if (info) {
- printk("btrfs: allowing degraded mounts\n");
- btrfs_set_opt(info->mount_opt, DEGRADED);
- }
+ 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");
- btrfs_set_opt(info->mount_opt, NODATASUM);
- }
+ 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");
- btrfs_set_opt(info->mount_opt, NODATACOW);
- btrfs_set_opt(info->mount_opt, NODATASUM);
- }
+ 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");
- btrfs_set_opt(info->mount_opt, SSD);
- }
+ 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");
- btrfs_set_opt(info->mount_opt, NOBARRIER);
- }
+ 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]);
- if (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);
- }
+ num = match_strdup(&args[0]);
+ if (num) {
+ info->max_extent = btrfs_parse_size(num);
+ kfree(num);
+
+ info->max_extent = max_t(u64,
+ 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]);
- if (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);
- }
+ num = match_strdup(&args[0]);
+ if (num) {
+ info->max_inline = btrfs_parse_size(num);
+ kfree(num);
+
+ info->max_inline = max_t(u64,
+ 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]);
- if (num) {
- info->alloc_start - btrfs_parse_size(num);
- kfree(num);
- printk("btrfs: allocations start at "
- "%Lu\n", info->alloc_start);
- }
+ num = match_strdup(&args[0]);
+ if (num) {
+ info->alloc_start = btrfs_parse_size(num);
+ kfree(num);
+ printk(KERN_INFO
+ "btrfs: allocations start at %llu\n",
+ info->alloc_start);
}
break;
default:
@@ -221,7 +203,61 @@ int btrfs_parse_options(char *options, s
}
}
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
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();
@@ -378,51 +424,36 @@ int btrfs_get_sb_bdev(struct file_system
s->s_flags |= MS_ACTIVE;
}
- if (subvol) {
- root = lookup_one_len(subvol, s->s_root, strlen(subvol));
- if (IS_ERR(root)) {
- up_write(&s->s_umount);
- deactivate_super(s);
- error = PTR_ERR(root);
- goto error;
- }
- if (!root->d_inode) {
- dput(root);
- up_write(&s->s_umount);
- deactivate_super(s);
- error = -ENXIO;
- goto error;
- }
- } else {
- root = dget(s->s_root);
+ root = lookup_one_len(subvol_name, s->s_root, strlen(subvol_name));
+ if (IS_ERR(root)) {
+ up_write(&s->s_umount);
+ deactivate_super(s);
+ error = PTR_ERR(root);
+ goto error;
+ }
+ if (!root->d_inode) {
+ dput(root);
+ up_write(&s->s_umount);
+ deactivate_super(s);
+ error = -ENXIO;
+ goto error;
}
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)
{
Index: btrfs-unstable/ctree.h
==================================================================---
btrfs-unstable.orig/ctree.h 2008-06-09 14:08:56.000000000 +0200
+++ btrfs-unstable/ctree.h 2008-06-10 10:40:38.000000000 +0200
@@ -1610,6 +1610,6 @@ int btrfs_delete_xattrs(struct btrfs_tra
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);
+
#endif
Index: btrfs-unstable/disk-io.c
==================================================================---
btrfs-unstable.orig/disk-io.c 2008-06-09 13:58:03.000000000 +0200
+++ btrfs-unstable/disk-io.c 2008-06-10 10:41:31.000000000 +0200
@@ -1266,8 +1266,11 @@ struct btrfs_root *open_ctree(struct sup
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),
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