#include <linux/fsnotify.h>
#include <linux/lockdep.h>
#include <linux/user_namespace.h>
+#include <linux/fs_context.h>
#include <uapi/linux/mount.h>
#include "internal.h"
EXPORT_SYMBOL(generic_shutdown_super);
+/**
+ * sget_fc - Find or create a superblock
+ * @fc: Filesystem context.
+ * @test: Comparison callback
+ * @set: Setup callback
+ *
+ * Find or create a superblock using the parameters stored in the filesystem
+ * context and the two callback functions.
+ *
+ * If an extant superblock is matched, then that will be returned with an
+ * elevated reference count that the caller must transfer or discard.
+ *
+ * If no match is made, a new superblock will be allocated and basic
+ * initialisation will be performed (s_type, s_fs_info and s_id will be set and
+ * the set() callback will be invoked), the superblock will be published and it
+ * will be returned in a partially constructed state with SB_BORN and SB_ACTIVE
+ * as yet unset.
+ */
+struct super_block *sget_fc(struct fs_context *fc,
+ int (*test)(struct super_block *, struct fs_context *),
+ int (*set)(struct super_block *, struct fs_context *))
+{
+ struct super_block *s = NULL;
+ struct super_block *old;
+ struct user_namespace *user_ns = fc->global ? &init_user_ns : fc->user_ns;
+ int err;
+
+ if (!(fc->sb_flags & SB_KERNMOUNT) &&
+ fc->purpose != FS_CONTEXT_FOR_SUBMOUNT) {
+ /* Don't allow mounting unless the caller has CAP_SYS_ADMIN
+ * over the namespace.
+ */
+ if (!(fc->fs_type->fs_flags & FS_USERNS_MOUNT)) {
+ if (!capable(CAP_SYS_ADMIN))
+ return ERR_PTR(-EPERM);
+ } else {
+ if (!ns_capable(fc->user_ns, CAP_SYS_ADMIN))
+ return ERR_PTR(-EPERM);
+ }
+ }
+
+retry:
+ spin_lock(&sb_lock);
+ if (test) {
+ hlist_for_each_entry(old, &fc->fs_type->fs_supers, s_instances) {
+ if (test(old, fc))
+ goto share_extant_sb;
+ }
+ }
+ if (!s) {
+ spin_unlock(&sb_lock);
+ s = alloc_super(fc->fs_type, fc->sb_flags, user_ns);
+ if (!s)
+ return ERR_PTR(-ENOMEM);
+ goto retry;
+ }
+
+ s->s_fs_info = fc->s_fs_info;
+ err = set(s, fc);
+ if (err) {
+ s->s_fs_info = NULL;
+ spin_unlock(&sb_lock);
+ destroy_unused_super(s);
+ return ERR_PTR(err);
+ }
+ fc->s_fs_info = NULL;
+ s->s_type = fc->fs_type;
+ strlcpy(s->s_id, s->s_type->name, sizeof(s->s_id));
+ list_add_tail(&s->s_list, &super_blocks);
+ hlist_add_head(&s->s_instances, &s->s_type->fs_supers);
+ spin_unlock(&sb_lock);
+ get_filesystem(s->s_type);
+ register_shrinker_prepared(&s->s_shrink);
+ return s;
+
+share_extant_sb:
+ if (user_ns != old->s_user_ns) {
+ spin_unlock(&sb_lock);
+ destroy_unused_super(s);
+ return ERR_PTR(-EBUSY);
+ }
+ if (!grab_super(old))
+ goto retry;
+ destroy_unused_super(s);
+ return old;
+}
+EXPORT_SYMBOL(sget_fc);
+
/**
* sget_userns - find or create a superblock
* @type: filesystem type superblock should belong to
}
/**
- * do_remount_sb - asks filesystem to change mount options.
- * @sb: superblock in question
- * @sb_flags: revised superblock flags
- * @data: the rest of options
- * @force: whether or not to force the change
+ * reconfigure_super - asks filesystem to change superblock parameters
+ * @fc: The superblock and configuration
*
- * Alters the mount options of a mounted file system.
+ * Alters the configuration parameters of a live superblock.
*/
-int do_remount_sb(struct super_block *sb, int sb_flags, void *data, int force)
+int reconfigure_super(struct fs_context *fc)
{
+ struct super_block *sb = fc->root->d_sb;
int retval;
- int remount_ro;
+ bool remount_ro = false;
+ bool force = fc->sb_flags & SB_FORCE;
+ if (fc->sb_flags_mask & ~MS_RMT_MASK)
+ return -EINVAL;
if (sb->s_writers.frozen != SB_UNFROZEN)
return -EBUSY;
+ retval = security_sb_remount(sb, fc->security);
+ if (retval)
+ return retval;
+
+ if (fc->sb_flags_mask & SB_RDONLY) {
#ifdef CONFIG_BLOCK
- if (!(sb_flags & SB_RDONLY) && bdev_read_only(sb->s_bdev))
- return -EACCES;
+ if (!(fc->sb_flags & SB_RDONLY) && bdev_read_only(sb->s_bdev))
+ return -EACCES;
#endif
- remount_ro = (sb_flags & SB_RDONLY) && !sb_rdonly(sb);
+ remount_ro = (fc->sb_flags & SB_RDONLY) && !sb_rdonly(sb);
+ }
if (remount_ro) {
if (!hlist_empty(&sb->s_pins)) {
return 0;
if (sb->s_writers.frozen != SB_UNFROZEN)
return -EBUSY;
- remount_ro = (sb_flags & SB_RDONLY) && !sb_rdonly(sb);
+ remount_ro = !sb_rdonly(sb);
}
}
shrink_dcache_sb(sb);
- /* If we are remounting RDONLY and current sb is read/write,
- make sure there are no rw files opened */
+ /* If we are reconfiguring to RDONLY and current sb is read/write,
+ * make sure there are no files open for writing.
+ */
if (remount_ro) {
if (force) {
sb->s_readonly_remount = 1;
}
}
- if (sb->s_op->remount_fs) {
- retval = sb->s_op->remount_fs(sb, &sb_flags, data);
+ if (fc->ops->reconfigure) {
+ retval = fc->ops->reconfigure(fc);
if (retval) {
if (!force)
goto cancel_readonly;
sb->s_type->name, retval);
}
}
- sb->s_flags = (sb->s_flags & ~MS_RMT_MASK) | (sb_flags & MS_RMT_MASK);
+
+ WRITE_ONCE(sb->s_flags, ((sb->s_flags & ~fc->sb_flags_mask) |
+ (fc->sb_flags & fc->sb_flags_mask)));
/* Needs to be ordered wrt mnt_is_readonly() */
smp_wmb();
sb->s_readonly_remount = 0;
down_write(&sb->s_umount);
if (sb->s_root && sb->s_bdev && (sb->s_flags & SB_BORN) &&
!sb_rdonly(sb)) {
- /*
- * What lock protects sb->s_flags??
- */
- do_remount_sb(sb, SB_RDONLY, NULL, 1);
+ struct fs_context *fc;
+
+ fc = fs_context_for_reconfigure(sb->s_root,
+ SB_RDONLY | SB_FORCE, SB_RDONLY);
+ if (!IS_ERR(fc)) {
+ if (parse_monolithic_mount_data(fc, NULL) == 0)
+ (void)reconfigure_super(fc);
+ put_fs_context(fc);
+ }
}
up_write(&sb->s_umount);
}
EXPORT_SYMBOL(mount_ns);
+int set_anon_super_fc(struct super_block *sb, struct fs_context *fc)
+{
+ return set_anon_super(sb, NULL);
+}
+EXPORT_SYMBOL(set_anon_super_fc);
+
+static int test_keyed_super(struct super_block *sb, struct fs_context *fc)
+{
+ return sb->s_fs_info == fc->s_fs_info;
+}
+
+static int test_single_super(struct super_block *s, struct fs_context *fc)
+{
+ return 1;
+}
+
+/**
+ * vfs_get_super - Get a superblock with a search key set in s_fs_info.
+ * @fc: The filesystem context holding the parameters
+ * @keying: How to distinguish superblocks
+ * @fill_super: Helper to initialise a new superblock
+ *
+ * Search for a superblock and create a new one if not found. The search
+ * criterion is controlled by @keying. If the search fails, a new superblock
+ * is created and @fill_super() is called to initialise it.
+ *
+ * @keying can take one of a number of values:
+ *
+ * (1) vfs_get_single_super - Only one superblock of this type may exist on the
+ * system. This is typically used for special system filesystems.
+ *
+ * (2) vfs_get_keyed_super - Multiple superblocks may exist, but they must have
+ * distinct keys (where the key is in s_fs_info). Searching for the same
+ * key again will turn up the superblock for that key.
+ *
+ * (3) vfs_get_independent_super - Multiple superblocks may exist and are
+ * unkeyed. Each call will get a new superblock.
+ *
+ * A permissions check is made by sget_fc() unless we're getting a superblock
+ * for a kernel-internal mount or a submount.
+ */
+int vfs_get_super(struct fs_context *fc,
+ enum vfs_get_super_keying keying,
+ int (*fill_super)(struct super_block *sb,
+ struct fs_context *fc))
+{
+ int (*test)(struct super_block *, struct fs_context *);
+ struct super_block *sb;
+
+ switch (keying) {
+ case vfs_get_single_super:
+ test = test_single_super;
+ break;
+ case vfs_get_keyed_super:
+ test = test_keyed_super;
+ break;
+ case vfs_get_independent_super:
+ test = NULL;
+ break;
+ default:
+ BUG();
+ }
+
+ sb = sget_fc(fc, test, set_anon_super_fc);
+ if (IS_ERR(sb))
+ return PTR_ERR(sb);
+
+ if (!sb->s_root) {
+ int err = fill_super(sb, fc);
+ if (err) {
+ deactivate_locked_super(sb);
+ return err;
+ }
+
+ sb->s_flags |= SB_ACTIVE;
+ }
+
+ BUG_ON(fc->root);
+ fc->root = dget(sb->s_root);
+ return 0;
+}
+EXPORT_SYMBOL(vfs_get_super);
+
#ifdef CONFIG_BLOCK
static int set_bdev_super(struct super_block *s, void *data)
{
}
EXPORT_SYMBOL(mount_nodev);
+static int reconfigure_single(struct super_block *s,
+ int flags, void *data)
+{
+ struct fs_context *fc;
+ int ret;
+
+ /* The caller really need to be passing fc down into mount_single(),
+ * then a chunk of this can be removed. [Bollocks -- AV]
+ * Better yet, reconfiguration shouldn't happen, but rather the second
+ * mount should be rejected if the parameters are not compatible.
+ */
+ fc = fs_context_for_reconfigure(s->s_root, flags, MS_RMT_MASK);
+ if (IS_ERR(fc))
+ return PTR_ERR(fc);
+
+ ret = parse_monolithic_mount_data(fc, data);
+ if (ret < 0)
+ goto out;
+
+ ret = reconfigure_super(fc);
+out:
+ put_fs_context(fc);
+ return ret;
+}
+
static int compare_single(struct super_block *s, void *p)
{
return 1;
return ERR_CAST(s);
if (!s->s_root) {
error = fill_super(s, data, flags & SB_SILENT ? 1 : 0);
- if (error) {
- deactivate_locked_super(s);
- return ERR_PTR(error);
- }
- s->s_flags |= SB_ACTIVE;
+ if (!error)
+ s->s_flags |= SB_ACTIVE;
} else {
- do_remount_sb(s, flags, data, 0);
+ error = reconfigure_single(s, flags, data);
+ }
+ if (unlikely(error)) {
+ deactivate_locked_super(s);
+ return ERR_PTR(error);
}
return dget(s->s_root);
}
EXPORT_SYMBOL(mount_single);
-struct dentry *
-mount_fs(struct file_system_type *type, int flags, const char *name, void *data)
+/**
+ * vfs_get_tree - Get the mountable root
+ * @fc: The superblock configuration context.
+ *
+ * The filesystem is invoked to get or create a superblock which can then later
+ * be used for mounting. The filesystem places a pointer to the root to be
+ * used for mounting in @fc->root.
+ */
+int vfs_get_tree(struct fs_context *fc)
{
- struct dentry *root;
struct super_block *sb;
- int error = -ENOMEM;
- void *sec_opts = NULL;
+ int error;
- if (data && !(type->fs_flags & FS_BINARY_MOUNTDATA)) {
- error = security_sb_eat_lsm_opts(data, &sec_opts);
- if (error)
- return ERR_PTR(error);
+ if (fc->fs_type->fs_flags & FS_REQUIRES_DEV && !fc->source) {
+ errorf(fc, "Filesystem requires source device");
+ return -ENOENT;
}
- root = type->mount(type, flags, name, data);
- if (IS_ERR(root)) {
- error = PTR_ERR(root);
- goto out_free_secdata;
+ if (fc->root)
+ return -EBUSY;
+
+ /* Get the mountable root in fc->root, with a ref on the root and a ref
+ * on the superblock.
+ */
+ error = fc->ops->get_tree(fc);
+ if (error < 0)
+ return error;
+
+ if (!fc->root) {
+ pr_err("Filesystem %s get_tree() didn't set fc->root\n",
+ fc->fs_type->name);
+ /* We don't know what the locking state of the superblock is -
+ * if there is a superblock.
+ */
+ BUG();
}
- sb = root->d_sb;
- BUG_ON(!sb);
+
+ sb = fc->root->d_sb;
WARN_ON(!sb->s_bdi);
+ if (fc->subtype && !sb->s_subtype) {
+ sb->s_subtype = fc->subtype;
+ fc->subtype = NULL;
+ }
+
/*
* Write barrier is for super_cache_count(). We place it before setting
* SB_BORN as the data dependency between the two functions is the
smp_wmb();
sb->s_flags |= SB_BORN;
- error = security_sb_set_mnt_opts(sb, sec_opts, 0, NULL);
- if (error)
- goto out_sb;
-
- if (!(flags & (MS_KERNMOUNT|MS_SUBMOUNT))) {
- error = security_sb_kern_mount(sb);
- if (error)
- goto out_sb;
+ error = security_sb_set_mnt_opts(sb, fc->security, 0, NULL);
+ if (unlikely(error)) {
+ fc_drop_locked(fc);
+ return error;
}
/*
* violate this rule.
*/
WARN((sb->s_maxbytes < 0), "%s set sb->s_maxbytes to "
- "negative value (%lld)\n", type->name, sb->s_maxbytes);
+ "negative value (%lld)\n", fc->fs_type->name, sb->s_maxbytes);
- up_write(&sb->s_umount);
- security_free_mnt_opts(&sec_opts);
- return root;
-out_sb:
- dput(root);
- deactivate_locked_super(sb);
-out_free_secdata:
- security_free_mnt_opts(&sec_opts);
- return ERR_PTR(error);
+ return 0;
}
+EXPORT_SYMBOL(vfs_get_tree);
/*
* Setup private BDI for given superblock. It gets automatically cleaned up
git.samba.org / sfrench / cifs-2.6.git / blobdiff