new helper: mount_subtree()
[pandora-kernel.git] / fs / btrfs / super.c
index 15634d4..17ee7fc 100644 (file)
@@ -40,6 +40,7 @@
 #include <linux/magic.h>
 #include <linux/slab.h>
 #include <linux/cleancache.h>
+#include <linux/mnt_namespace.h>
 #include "compat.h"
 #include "delayed-inode.h"
 #include "ctree.h"
@@ -58,6 +59,7 @@
 #include <trace/events/btrfs.h>
 
 static const struct super_operations btrfs_super_ops;
+static struct file_system_type btrfs_fs_type;
 
 static const char *btrfs_decode_error(struct btrfs_fs_info *fs_info, int errno,
                                      char nbuf[16])
@@ -162,7 +164,7 @@ enum {
        Opt_notreelog, Opt_ratio, Opt_flushoncommit, Opt_discard,
        Opt_space_cache, Opt_clear_cache, Opt_user_subvol_rm_allowed,
        Opt_enospc_debug, Opt_subvolrootid, Opt_defrag,
-       Opt_inode_cache, Opt_err,
+       Opt_inode_cache, Opt_no_space_cache, Opt_recovery, Opt_err,
 };
 
 static match_table_t tokens = {
@@ -195,6 +197,8 @@ static match_table_t tokens = {
        {Opt_subvolrootid, "subvolrootid=%d"},
        {Opt_defrag, "autodefrag"},
        {Opt_inode_cache, "inode_cache"},
+       {Opt_no_space_cache, "nospace_cache"},
+       {Opt_recovery, "recovery"},
        {Opt_err, NULL},
 };
 
@@ -206,14 +210,19 @@ int btrfs_parse_options(struct btrfs_root *root, char *options)
 {
        struct btrfs_fs_info *info = root->fs_info;
        substring_t args[MAX_OPT_ARGS];
-       char *p, *num, *orig;
+       char *p, *num, *orig = NULL;
+       u64 cache_gen;
        int intarg;
        int ret = 0;
        char *compress_type;
        bool compress_force = false;
 
+       cache_gen = btrfs_super_cache_generation(root->fs_info->super_copy);
+       if (cache_gen)
+               btrfs_set_opt(info->mount_opt, SPACE_CACHE);
+
        if (!options)
-               return 0;
+               goto out;
 
        /*
         * strsep changes the string, duplicate it because parse_options
@@ -360,9 +369,12 @@ int btrfs_parse_options(struct btrfs_root *root, char *options)
                        btrfs_set_opt(info->mount_opt, DISCARD);
                        break;
                case Opt_space_cache:
-                       printk(KERN_INFO "btrfs: enabling disk space caching\n");
                        btrfs_set_opt(info->mount_opt, SPACE_CACHE);
                        break;
+               case Opt_no_space_cache:
+                       printk(KERN_INFO "btrfs: disabling disk space caching\n");
+                       btrfs_clear_opt(info->mount_opt, SPACE_CACHE);
+                       break;
                case Opt_inode_cache:
                        printk(KERN_INFO "btrfs: enabling inode map caching\n");
                        btrfs_set_opt(info->mount_opt, INODE_MAP_CACHE);
@@ -381,6 +393,10 @@ int btrfs_parse_options(struct btrfs_root *root, char *options)
                        printk(KERN_INFO "btrfs: enabling auto defrag");
                        btrfs_set_opt(info->mount_opt, AUTO_DEFRAG);
                        break;
+               case Opt_recovery:
+                       printk(KERN_INFO "btrfs: enabling auto recovery");
+                       btrfs_set_opt(info->mount_opt, RECOVERY);
+                       break;
                case Opt_err:
                        printk(KERN_INFO "btrfs: unrecognized mount option "
                               "'%s'\n", p);
@@ -391,6 +407,8 @@ int btrfs_parse_options(struct btrfs_root *root, char *options)
                }
        }
 out:
+       if (!ret && btrfs_test_opt(root, SPACE_CACHE))
+               printk(KERN_INFO "btrfs: disk space caching is enabled\n");
        kfree(orig);
        return ret;
 }
@@ -406,12 +424,12 @@ static int btrfs_parse_early_options(const char *options, fmode_t flags,
                u64 *subvol_rootid, struct btrfs_fs_devices **fs_devices)
 {
        substring_t args[MAX_OPT_ARGS];
-       char *opts, *orig, *p;
+       char *device_name, *opts, *orig, *p;
        int error = 0;
        int intarg;
 
        if (!options)
-               goto out;
+               return 0;
 
        /*
         * strsep changes the string, duplicate it because parse_options
@@ -430,6 +448,7 @@ static int btrfs_parse_early_options(const char *options, fmode_t flags,
                token = match_token(p, tokens, args);
                switch (token) {
                case Opt_subvol:
+                       kfree(*subvol_name);
                        *subvol_name = match_strdup(&args[0]);
                        break;
                case Opt_subvolid:
@@ -457,29 +476,24 @@ static int btrfs_parse_early_options(const char *options, fmode_t flags,
                        }
                        break;
                case Opt_device:
-                       error = btrfs_scan_one_device(match_strdup(&args[0]),
+                       device_name = match_strdup(&args[0]);
+                       if (!device_name) {
+                               error = -ENOMEM;
+                               goto out;
+                       }
+                       error = btrfs_scan_one_device(device_name,
                                        flags, holder, fs_devices);
+                       kfree(device_name);
                        if (error)
-                               goto out_free_opts;
+                               goto out;
                        break;
                default:
                        break;
                }
        }
 
- out_free_opts:
+out:
        kfree(orig);
- out:
-       /*
-        * If no subvolume name is specified we use the default one.  Allocate
-        * a copy of the string "." 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(".", GFP_KERNEL);
-               if (!*subvol_name)
-                       return -ENOMEM;
-       }
        return error;
 }
 
@@ -492,7 +506,6 @@ static struct dentry *get_default_root(struct super_block *sb,
        struct btrfs_path *path;
        struct btrfs_key location;
        struct inode *inode;
-       struct dentry *dentry;
        u64 dir_id;
        int new = 0;
 
@@ -517,7 +530,7 @@ static struct dentry *get_default_root(struct super_block *sb,
         * will mount by default if we haven't been given a specific subvolume
         * to mount.
         */
-       dir_id = btrfs_super_root_dir(&root->fs_info->super_copy);
+       dir_id = btrfs_super_root_dir(root->fs_info->super_copy);
        di = btrfs_lookup_dir_item(NULL, root, path, dir_id, "default", 7, 0);
        if (IS_ERR(di)) {
                btrfs_free_path(path);
@@ -566,29 +579,7 @@ setup_root:
                return dget(sb->s_root);
        }
 
-       if (new) {
-               const struct qstr name = { .name = "/", .len = 1 };
-
-               /*
-                * New inode, we need to make the dentry a sibling of s_root so
-                * everything gets cleaned up properly on unmount.
-                */
-               dentry = d_alloc(sb->s_root, &name);
-               if (!dentry) {
-                       iput(inode);
-                       return ERR_PTR(-ENOMEM);
-               }
-               d_splice_alias(inode, dentry);
-       } else {
-               /*
-                * We found the inode in cache, just find a dentry for it and
-                * put the reference to the inode we just got.
-                */
-               dentry = d_find_alias(inode);
-               iput(inode);
-       }
-
-       return dentry;
+       return d_obtain_alias(inode);
 }
 
 static int btrfs_fill_super(struct super_block *sb,
@@ -719,6 +710,8 @@ static int btrfs_show_options(struct seq_file *seq, struct vfsmount *vfs)
                seq_puts(seq, ",noacl");
        if (btrfs_test_opt(root, SPACE_CACHE))
                seq_puts(seq, ",space_cache");
+       else
+               seq_puts(seq, ",nospace_cache");
        if (btrfs_test_opt(root, CLEAR_CACHE))
                seq_puts(seq, ",clear_cache");
        if (btrfs_test_opt(root, USER_SUBVOL_RM_ALLOWED))
@@ -753,6 +746,111 @@ static int btrfs_set_super(struct super_block *s, void *data)
        return set_anon_super(s, data);
 }
 
+/*
+ * subvolumes are identified by ino 256
+ */
+static inline int is_subvolume_inode(struct inode *inode)
+{
+       if (inode && inode->i_ino == BTRFS_FIRST_FREE_OBJECTID)
+               return 1;
+       return 0;
+}
+
+/*
+ * This will strip out the subvol=%s argument for an argument string and add
+ * subvolid=0 to make sure we get the actual tree root for path walking to the
+ * subvol we want.
+ */
+static char *setup_root_args(char *args)
+{
+       unsigned copied = 0;
+       unsigned len = strlen(args) + 2;
+       char *pos;
+       char *ret;
+
+       /*
+        * We need the same args as before, but minus
+        *
+        * subvol=a
+        *
+        * and add
+        *
+        * subvolid=0
+        *
+        * which is a difference of 2 characters, so we allocate strlen(args) +
+        * 2 characters.
+        */
+       ret = kzalloc(len * sizeof(char), GFP_NOFS);
+       if (!ret)
+               return NULL;
+       pos = strstr(args, "subvol=");
+
+       /* This shouldn't happen, but just in case.. */
+       if (!pos) {
+               kfree(ret);
+               return NULL;
+       }
+
+       /*
+        * The subvol=<> arg is not at the front of the string, copy everybody
+        * up to that into ret.
+        */
+       if (pos != args) {
+               *pos = '\0';
+               strcpy(ret, args);
+               copied += strlen(args);
+               pos++;
+       }
+
+       strncpy(ret + copied, "subvolid=0", len - copied);
+
+       /* Length of subvolid=0 */
+       copied += 10;
+
+       /*
+        * If there is no , after the subvol= option then we know there's no
+        * other options and we can just return.
+        */
+       pos = strchr(pos, ',');
+       if (!pos)
+               return ret;
+
+       /* Copy the rest of the arguments into our buffer */
+       strncpy(ret + copied, pos, len - copied);
+       copied += strlen(pos);
+
+       return ret;
+}
+
+static struct dentry *mount_subvol(const char *subvol_name, int flags,
+                                  const char *device_name, char *data)
+{
+       struct dentry *root;
+       struct vfsmount *mnt;
+       char *newargs;
+
+       newargs = setup_root_args(data);
+       if (!newargs)
+               return ERR_PTR(-ENOMEM);
+       mnt = vfs_kern_mount(&btrfs_fs_type, flags, device_name,
+                            newargs);
+       kfree(newargs);
+       if (IS_ERR(mnt))
+               return ERR_CAST(mnt);
+
+       root = mount_subtree(mnt, subvol_name);
+
+       if (!IS_ERR(root) && !is_subvolume_inode(root->d_inode)) {
+               struct super_block *s = root->d_sb;
+               dput(root);
+               root = ERR_PTR(-EINVAL);
+               deactivate_locked_super(s);
+               printk(KERN_ERR "btrfs: '%s' is not a valid subvolume\n",
+                               subvol_name);
+       }
+
+       return root;
+}
 
 /*
  * Find a superblock for the given device / mount point.
@@ -767,7 +865,6 @@ static struct dentry *btrfs_mount(struct file_system_type *fs_type, int flags,
        struct super_block *s;
        struct dentry *root;
        struct btrfs_fs_devices *fs_devices = NULL;
-       struct btrfs_root *tree_root = NULL;
        struct btrfs_fs_info *fs_info = NULL;
        fmode_t mode = FMODE_READ;
        char *subvol_name = NULL;
@@ -781,21 +878,20 @@ static struct dentry *btrfs_mount(struct file_system_type *fs_type, int flags,
        error = btrfs_parse_early_options(data, mode, fs_type,
                                          &subvol_name, &subvol_objectid,
                                          &subvol_rootid, &fs_devices);
-       if (error)
+       if (error) {
+               kfree(subvol_name);
                return ERR_PTR(error);
+       }
 
-       error = btrfs_scan_one_device(device_name, mode, fs_type, &fs_devices);
-       if (error)
-               goto error_free_subvol_name;
+       if (subvol_name) {
+               root = mount_subvol(subvol_name, flags, device_name, data);
+               kfree(subvol_name);
+               return root;
+       }
 
-       error = btrfs_open_devices(fs_devices, mode, fs_type);
+       error = btrfs_scan_one_device(device_name, mode, fs_type, &fs_devices);
        if (error)
-               goto error_free_subvol_name;
-
-       if (!(flags & MS_RDONLY) && fs_devices->rw_devices == 0) {
-               error = -EACCES;
-               goto error_close_devices;
-       }
+               return ERR_PTR(error);
 
        /*
         * Setup a dummy root and fs_info for test/set super.  This is because
@@ -804,19 +900,40 @@ static struct dentry *btrfs_mount(struct file_system_type *fs_type, int flags,
         * then open_ctree will properly initialize everything later.
         */
        fs_info = kzalloc(sizeof(struct btrfs_fs_info), GFP_NOFS);
-       tree_root = kzalloc(sizeof(struct btrfs_root), GFP_NOFS);
-       if (!fs_info || !tree_root) {
+       if (!fs_info)
+               return ERR_PTR(-ENOMEM);
+
+       fs_info->tree_root = kzalloc(sizeof(struct btrfs_root), GFP_NOFS);
+       if (!fs_info->tree_root) {
                error = -ENOMEM;
-               goto error_close_devices;
+               goto error_fs_info;
        }
-       fs_info->tree_root = tree_root;
+       fs_info->tree_root->fs_info = fs_info;
        fs_info->fs_devices = fs_devices;
-       tree_root->fs_info = fs_info;
+
+       fs_info->super_copy = kzalloc(BTRFS_SUPER_INFO_SIZE, GFP_NOFS);
+       fs_info->super_for_commit = kzalloc(BTRFS_SUPER_INFO_SIZE, GFP_NOFS);
+       if (!fs_info->super_copy || !fs_info->super_for_commit) {
+               error = -ENOMEM;
+               goto error_fs_info;
+       }
+
+       error = btrfs_open_devices(fs_devices, mode, fs_type);
+       if (error)
+               goto error_fs_info;
+
+       if (!(flags & MS_RDONLY) && fs_devices->rw_devices == 0) {
+               error = -EACCES;
+               goto error_close_devices;
+       }
 
        bdev = fs_devices->latest_bdev;
-       s = sget(fs_type, btrfs_test_super, btrfs_set_super, tree_root);
-       if (IS_ERR(s))
-               goto error_s;
+       s = sget(fs_type, btrfs_test_super, btrfs_set_super,
+                fs_info->tree_root);
+       if (IS_ERR(s)) {
+               error = PTR_ERR(s);
+               goto error_close_devices;
+       }
 
        if (s->s_root) {
                if ((flags ^ s->s_flags) & MS_RDONLY) {
@@ -826,75 +943,35 @@ static struct dentry *btrfs_mount(struct file_system_type *fs_type, int flags,
                }
 
                btrfs_close_devices(fs_devices);
-               kfree(fs_info);
-               kfree(tree_root);
+               free_fs_info(fs_info);
        } else {
                char b[BDEVNAME_SIZE];
 
                s->s_flags = flags | MS_NOSEC;
                strlcpy(s->s_id, bdevname(bdev, b), sizeof(s->s_id));
+               btrfs_sb(s)->fs_info->bdev_holder = fs_type;
                error = btrfs_fill_super(s, fs_devices, data,
                                         flags & MS_SILENT ? 1 : 0);
                if (error) {
                        deactivate_locked_super(s);
-                       goto error_free_subvol_name;
+                       return ERR_PTR(error);
                }
 
-               btrfs_sb(s)->fs_info->bdev_holder = fs_type;
                s->s_flags |= MS_ACTIVE;
        }
 
-       /* if they gave us a subvolume name bind mount into that */
-       if (strcmp(subvol_name, ".")) {
-               struct dentry *new_root;
-
-               root = get_default_root(s, subvol_rootid);
-               if (IS_ERR(root)) {
-                       error = PTR_ERR(root);
-                       deactivate_locked_super(s);
-                       goto error_free_subvol_name;
-               }
-
-               mutex_lock(&root->d_inode->i_mutex);
-               new_root = lookup_one_len(subvol_name, root,
-                                     strlen(subvol_name));
-               mutex_unlock(&root->d_inode->i_mutex);
-
-               if (IS_ERR(new_root)) {
-                       dput(root);
-                       deactivate_locked_super(s);
-                       error = PTR_ERR(new_root);
-                       goto error_free_subvol_name;
-               }
-               if (!new_root->d_inode) {
-                       dput(root);
-                       dput(new_root);
-                       deactivate_locked_super(s);
-                       error = -ENXIO;
-                       goto error_free_subvol_name;
-               }
-               dput(root);
-               root = new_root;
-       } else {
-               root = get_default_root(s, subvol_objectid);
-               if (IS_ERR(root)) {
-                       error = PTR_ERR(root);
-                       deactivate_locked_super(s);
-                       goto error_free_subvol_name;
-               }
+       root = get_default_root(s, subvol_objectid);
+       if (IS_ERR(root)) {
+               deactivate_locked_super(s);
+               return root;
        }
 
-       kfree(subvol_name);
        return root;
 
-error_s:
-       error = PTR_ERR(s);
 error_close_devices:
        btrfs_close_devices(fs_devices);
-       kfree(fs_info);
-       kfree(tree_root);
-error_free_subvol_name:
-       kfree(subvol_name);
+error_fs_info:
+       free_fs_info(fs_info);
        return ERR_PTR(error);
 }
 
@@ -919,7 +996,7 @@ static int btrfs_remount(struct super_block *sb, int *flags, char *data)
                if (root->fs_info->fs_devices->rw_devices == 0)
                        return -EACCES;
 
-               if (btrfs_super_log_root(&root->fs_info->super_copy) != 0)
+               if (btrfs_super_log_root(root->fs_info->super_copy) != 0)
                        return -EINVAL;
 
                ret = btrfs_cleanup_fs_roots(root->fs_info);
@@ -1085,7 +1162,7 @@ static int btrfs_calc_avail_data_space(struct btrfs_root *root, u64 *free_bytes)
 static int btrfs_statfs(struct dentry *dentry, struct kstatfs *buf)
 {
        struct btrfs_root *root = btrfs_sb(dentry->d_sb);
-       struct btrfs_super_block *disk_super = &root->fs_info->super_copy;
+       struct btrfs_super_block *disk_super = root->fs_info->super_copy;
        struct list_head *head = &root->fs_info->space_info;
        struct btrfs_space_info *found;
        u64 total_used = 0;