[T106][ZXW-22]7520V3SCV2.01.01.02P42U09_VEC_V0.8_AP_VEC origin source commit
Change-Id: Ic6e05d89ecd62fc34f82b23dcf306c93764aec4b
diff --git a/ap/os/linux/linux-3.4.x/fs/super.c b/ap/os/linux/linux-3.4.x/fs/super.c
new file mode 100644
index 0000000..d0154e5
--- /dev/null
+++ b/ap/os/linux/linux-3.4.x/fs/super.c
@@ -0,0 +1,1258 @@
+/*
+ * linux/fs/super.c
+ *
+ * Copyright (C) 1991, 1992 Linus Torvalds
+ *
+ * super.c contains code to handle: - mount structures
+ * - super-block tables
+ * - filesystem drivers list
+ * - mount system call
+ * - umount system call
+ * - ustat system call
+ *
+ * GK 2/5/95 - Changed to support mounting the root fs via NFS
+ *
+ * Added kerneld support: Jacques Gelinas and Bjorn Ekwall
+ * Added change_root: Werner Almesberger & Hans Lermen, Feb '96
+ * Added options to /proc/mounts:
+ * Torbjörn Lindh (torbjorn.lindh@gopta.se), April 14, 1996.
+ * Added devfs support: Richard Gooch <rgooch@atnf.csiro.au>, 13-JAN-1998
+ * Heavily rewritten for 'one fs - one tree' dcache architecture. AV, Mar 2000
+ */
+
+#include <linux/export.h>
+#include <linux/slab.h>
+#include <linux/acct.h>
+#include <linux/blkdev.h>
+#include <linux/mount.h>
+#include <linux/security.h>
+#include <linux/writeback.h> /* for the emergency remount stuff */
+#include <linux/idr.h>
+#include <linux/mutex.h>
+#include <linux/backing-dev.h>
+#include <linux/rculist_bl.h>
+#include <linux/cleancache.h>
+#include <linux/fsnotify.h>
+#include "internal.h"
+
+
+LIST_HEAD(super_blocks);
+DEFINE_SPINLOCK(sb_lock);
+
+/*
+ * One thing we have to be careful of with a per-sb shrinker is that we don't
+ * drop the last active reference to the superblock from within the shrinker.
+ * If that happens we could trigger unregistering the shrinker from within the
+ * shrinker path and that leads to deadlock on the shrinker_rwsem. Hence we
+ * take a passive reference to the superblock to avoid this from occurring.
+ */
+static int prune_super(struct shrinker *shrink, struct shrink_control *sc)
+{
+ struct super_block *sb;
+ int fs_objects = 0;
+ int total_objects;
+
+ sb = container_of(shrink, struct super_block, s_shrink);
+
+ /*
+ * Deadlock avoidance. We may hold various FS locks, and we don't want
+ * to recurse into the FS that called us in clear_inode() and friends..
+ */
+ if (sc->nr_to_scan && !(sc->gfp_mask & __GFP_FS))
+ return -1;
+
+ if (!grab_super_passive(sb))
+ return !sc->nr_to_scan ? 0 : -1;
+
+ if (sb->s_op && sb->s_op->nr_cached_objects)
+ fs_objects = sb->s_op->nr_cached_objects(sb);
+
+ total_objects = sb->s_nr_dentry_unused +
+ sb->s_nr_inodes_unused + fs_objects + 1;
+ if (!total_objects)
+ total_objects = 1;
+
+ if (sc->nr_to_scan) {
+ int dentries;
+ int inodes;
+
+ /* proportion the scan between the caches */
+ dentries = (sc->nr_to_scan * sb->s_nr_dentry_unused) /
+ total_objects;
+ inodes = (sc->nr_to_scan * sb->s_nr_inodes_unused) /
+ total_objects;
+ if (fs_objects)
+ fs_objects = (sc->nr_to_scan * fs_objects) /
+ total_objects;
+ /*
+ * prune the dcache first as the icache is pinned by it, then
+ * prune the icache, followed by the filesystem specific caches
+ */
+ prune_dcache_sb(sb, dentries);
+ prune_icache_sb(sb, inodes);
+
+ if (fs_objects && sb->s_op->free_cached_objects) {
+ sb->s_op->free_cached_objects(sb, fs_objects);
+ fs_objects = sb->s_op->nr_cached_objects(sb);
+ }
+ total_objects = sb->s_nr_dentry_unused +
+ sb->s_nr_inodes_unused + fs_objects;
+ }
+
+ total_objects = (total_objects / 100) * sysctl_vfs_cache_pressure;
+ drop_super(sb);
+ return total_objects;
+}
+
+/**
+ * alloc_super - create new superblock
+ * @type: filesystem type superblock should belong to
+ *
+ * Allocates and initializes a new &struct super_block. alloc_super()
+ * returns a pointer new superblock or %NULL if allocation had failed.
+ */
+static struct super_block *alloc_super(struct file_system_type *type)
+{
+ struct super_block *s = kzalloc(sizeof(struct super_block), GFP_USER);
+ static const struct super_operations default_op;
+
+ if (s) {
+ if (security_sb_alloc(s)) {
+ kfree(s);
+ s = NULL;
+ goto out;
+ }
+#ifdef CONFIG_SMP
+ s->s_files = alloc_percpu(struct list_head);
+ if (!s->s_files) {
+ security_sb_free(s);
+ kfree(s);
+ s = NULL;
+ goto out;
+ } else {
+ int i;
+
+ for_each_possible_cpu(i)
+ INIT_LIST_HEAD(per_cpu_ptr(s->s_files, i));
+ }
+#else
+ INIT_LIST_HEAD(&s->s_files);
+#endif
+ s->s_bdi = &default_backing_dev_info;
+ INIT_HLIST_NODE(&s->s_instances);
+ INIT_HLIST_BL_HEAD(&s->s_anon);
+ INIT_LIST_HEAD(&s->s_inodes);
+ INIT_LIST_HEAD(&s->s_dentry_lru);
+ INIT_LIST_HEAD(&s->s_inode_lru);
+ spin_lock_init(&s->s_inode_lru_lock);
+ INIT_LIST_HEAD(&s->s_mounts);
+ init_rwsem(&s->s_umount);
+ mutex_init(&s->s_lock);
+ lockdep_set_class(&s->s_umount, &type->s_umount_key);
+ /*
+ * The locking rules for s_lock are up to the
+ * filesystem. For example ext3fs has different
+ * lock ordering than usbfs:
+ */
+ lockdep_set_class(&s->s_lock, &type->s_lock_key);
+ /*
+ * sget() can have s_umount recursion.
+ *
+ * When it cannot find a suitable sb, it allocates a new
+ * one (this one), and tries again to find a suitable old
+ * one.
+ *
+ * In case that succeeds, it will acquire the s_umount
+ * lock of the old one. Since these are clearly distrinct
+ * locks, and this object isn't exposed yet, there's no
+ * risk of deadlocks.
+ *
+ * Annotate this by putting this lock in a different
+ * subclass.
+ */
+ down_write_nested(&s->s_umount, SINGLE_DEPTH_NESTING);
+ s->s_count = 1;
+ atomic_set(&s->s_active, 1);
+ mutex_init(&s->s_vfs_rename_mutex);
+ lockdep_set_class(&s->s_vfs_rename_mutex, &type->s_vfs_rename_key);
+ mutex_init(&s->s_dquot.dqio_mutex);
+ mutex_init(&s->s_dquot.dqonoff_mutex);
+ init_rwsem(&s->s_dquot.dqptr_sem);
+ init_waitqueue_head(&s->s_wait_unfrozen);
+ s->s_maxbytes = MAX_NON_LFS;
+ s->s_op = &default_op;
+ s->s_time_gran = 1000000000;
+ s->cleancache_poolid = -1;
+
+ s->s_shrink.seeks = DEFAULT_SEEKS;
+ s->s_shrink.shrink = prune_super;
+ s->s_shrink.batch = 1024;
+ }
+out:
+ return s;
+}
+
+/**
+ * destroy_super - frees a superblock
+ * @s: superblock to free
+ *
+ * Frees a superblock.
+ */
+static inline void destroy_super(struct super_block *s)
+{
+#ifdef CONFIG_SMP
+ free_percpu(s->s_files);
+#endif
+ security_sb_free(s);
+ WARN_ON(!list_empty(&s->s_mounts));
+ kfree(s->s_subtype);
+ kfree(s->s_options);
+ kfree(s);
+}
+
+/* Superblock refcounting */
+
+/*
+ * Drop a superblock's refcount. The caller must hold sb_lock.
+ */
+static void __put_super(struct super_block *sb)
+{
+ if (!--sb->s_count) {
+ list_del_init(&sb->s_list);
+ destroy_super(sb);
+ }
+}
+
+/**
+ * put_super - drop a temporary reference to superblock
+ * @sb: superblock in question
+ *
+ * Drops a temporary reference, frees superblock if there's no
+ * references left.
+ */
+static void put_super(struct super_block *sb)
+{
+ spin_lock(&sb_lock);
+ __put_super(sb);
+ spin_unlock(&sb_lock);
+}
+
+
+/**
+ * deactivate_locked_super - drop an active reference to superblock
+ * @s: superblock to deactivate
+ *
+ * Drops an active reference to superblock, converting it into a temprory
+ * one if there is no other active references left. In that case we
+ * tell fs driver to shut it down and drop the temporary reference we
+ * had just acquired.
+ *
+ * Caller holds exclusive lock on superblock; that lock is released.
+ */
+void deactivate_locked_super(struct super_block *s)
+{
+ struct file_system_type *fs = s->s_type;
+ if (atomic_dec_and_test(&s->s_active)) {
+ cleancache_invalidate_fs(s);
+ fs->kill_sb(s);
+
+ /* caches are now gone, we can safely kill the shrinker now */
+ unregister_shrinker(&s->s_shrink);
+
+ /*
+ * We need to call rcu_barrier so all the delayed rcu free
+ * inodes are flushed before we release the fs module.
+ */
+ rcu_barrier();
+ put_filesystem(fs);
+ put_super(s);
+ } else {
+ up_write(&s->s_umount);
+ }
+}
+
+EXPORT_SYMBOL(deactivate_locked_super);
+
+/**
+ * deactivate_super - drop an active reference to superblock
+ * @s: superblock to deactivate
+ *
+ * Variant of deactivate_locked_super(), except that superblock is *not*
+ * locked by caller. If we are going to drop the final active reference,
+ * lock will be acquired prior to that.
+ */
+void deactivate_super(struct super_block *s)
+{
+ if (!atomic_add_unless(&s->s_active, -1, 1)) {
+ down_write(&s->s_umount);
+ deactivate_locked_super(s);
+ }
+}
+
+EXPORT_SYMBOL(deactivate_super);
+
+/**
+ * grab_super - acquire an active reference
+ * @s: reference we are trying to make active
+ *
+ * Tries to acquire an active reference. grab_super() is used when we
+ * had just found a superblock in super_blocks or fs_type->fs_supers
+ * and want to turn it into a full-blown active reference. grab_super()
+ * is called with sb_lock held and drops it. Returns 1 in case of
+ * success, 0 if we had failed (superblock contents was already dead or
+ * dying when grab_super() had been called). Note that this is only
+ * called for superblocks not in rundown mode (== ones still on ->fs_supers
+ * of their type), so increment of ->s_count is OK here.
+ */
+static int grab_super(struct super_block *s) __releases(sb_lock)
+{
+ s->s_count++;
+ spin_unlock(&sb_lock);
+ down_write(&s->s_umount);
+ if ((s->s_flags & MS_BORN) && atomic_inc_not_zero(&s->s_active)) {
+ put_super(s);
+ return 1;
+ }
+ up_write(&s->s_umount);
+ put_super(s);
+ return 0;
+}
+
+/*
+ * grab_super_passive - acquire a passive reference
+ * @s: reference we are trying to grab
+ *
+ * Tries to acquire a passive reference. This is used in places where we
+ * cannot take an active reference but we need to ensure that the
+ * superblock does not go away while we are working on it. It returns
+ * false if a reference was not gained, and returns true with the s_umount
+ * lock held in read mode if a reference is gained. On successful return,
+ * the caller must drop the s_umount lock and the passive reference when
+ * done.
+ */
+bool grab_super_passive(struct super_block *sb)
+{
+ spin_lock(&sb_lock);
+ if (hlist_unhashed(&sb->s_instances)) {
+ spin_unlock(&sb_lock);
+ return false;
+ }
+
+ sb->s_count++;
+ spin_unlock(&sb_lock);
+
+ if (down_read_trylock(&sb->s_umount)) {
+ if (sb->s_root && (sb->s_flags & MS_BORN))
+ return true;
+ up_read(&sb->s_umount);
+ }
+
+ put_super(sb);
+ return false;
+}
+
+/*
+ * Superblock locking. We really ought to get rid of these two.
+ */
+void lock_super(struct super_block * sb)
+{
+ mutex_lock(&sb->s_lock);
+}
+
+void unlock_super(struct super_block * sb)
+{
+ mutex_unlock(&sb->s_lock);
+}
+
+EXPORT_SYMBOL(lock_super);
+EXPORT_SYMBOL(unlock_super);
+
+/**
+ * generic_shutdown_super - common helper for ->kill_sb()
+ * @sb: superblock to kill
+ *
+ * generic_shutdown_super() does all fs-independent work on superblock
+ * shutdown. Typical ->kill_sb() should pick all fs-specific objects
+ * that need destruction out of superblock, call generic_shutdown_super()
+ * and release aforementioned objects. Note: dentries and inodes _are_
+ * taken care of and do not need specific handling.
+ *
+ * Upon calling this function, the filesystem may no longer alter or
+ * rearrange the set of dentries belonging to this super_block, nor may it
+ * change the attachments of dentries to inodes.
+ */
+void generic_shutdown_super(struct super_block *sb)
+{
+ const struct super_operations *sop = sb->s_op;
+
+ if (sb->s_root) {
+ shrink_dcache_for_umount(sb);
+ sync_filesystem(sb);
+ sb->s_flags &= ~MS_ACTIVE;
+
+ fsnotify_unmount_inodes(&sb->s_inodes);
+
+ evict_inodes(sb);
+
+ if (sop->put_super)
+ sop->put_super(sb);
+
+ if (!list_empty(&sb->s_inodes)) {
+ printk("VFS: Busy inodes after unmount of %s. "
+ "Self-destruct in 5 seconds. Have a nice day...\n",
+ sb->s_id);
+ }
+ }
+ spin_lock(&sb_lock);
+ /* should be initialized for __put_super_and_need_restart() */
+ hlist_del_init(&sb->s_instances);
+ spin_unlock(&sb_lock);
+ up_write(&sb->s_umount);
+}
+
+EXPORT_SYMBOL(generic_shutdown_super);
+
+/**
+ * sget - find or create a superblock
+ * @type: filesystem type superblock should belong to
+ * @test: comparison callback
+ * @set: setup callback
+ * @data: argument to each of them
+ */
+struct super_block *sget(struct file_system_type *type,
+ int (*test)(struct super_block *,void *),
+ int (*set)(struct super_block *,void *),
+ void *data)
+{
+ struct super_block *s = NULL;
+ struct hlist_node *node;
+ struct super_block *old;
+ int err;
+
+retry:
+ spin_lock(&sb_lock);
+ if (test) {
+ hlist_for_each_entry(old, node, &type->fs_supers, s_instances) {
+ if (!test(old, data))
+ continue;
+ if (!grab_super(old))
+ goto retry;
+ if (s) {
+ up_write(&s->s_umount);
+ destroy_super(s);
+ s = NULL;
+ }
+ return old;
+ }
+ }
+ if (!s) {
+ spin_unlock(&sb_lock);
+ s = alloc_super(type);
+ if (!s)
+ return ERR_PTR(-ENOMEM);
+ goto retry;
+ }
+
+ err = set(s, data);
+ if (err) {
+ spin_unlock(&sb_lock);
+ up_write(&s->s_umount);
+ destroy_super(s);
+ return ERR_PTR(err);
+ }
+ s->s_type = type;
+ strlcpy(s->s_id, type->name, sizeof(s->s_id));
+ list_add_tail(&s->s_list, &super_blocks);
+ hlist_add_head(&s->s_instances, &type->fs_supers);
+ spin_unlock(&sb_lock);
+ get_filesystem(type);
+ register_shrinker(&s->s_shrink);
+ return s;
+}
+
+EXPORT_SYMBOL(sget);
+
+void drop_super(struct super_block *sb)
+{
+ up_read(&sb->s_umount);
+ put_super(sb);
+}
+
+EXPORT_SYMBOL(drop_super);
+
+/**
+ * sync_supers - helper for periodic superblock writeback
+ *
+ * Call the write_super method if present on all dirty superblocks in
+ * the system. This is for the periodic writeback used by most older
+ * filesystems. For data integrity superblock writeback use
+ * sync_filesystems() instead.
+ *
+ * Note: check the dirty flag before waiting, so we don't
+ * hold up the sync while mounting a device. (The newly
+ * mounted device won't need syncing.)
+ */
+void sync_supers(void)
+{
+ struct super_block *sb, *p = NULL;
+
+ spin_lock(&sb_lock);
+ list_for_each_entry(sb, &super_blocks, s_list) {
+ if (hlist_unhashed(&sb->s_instances))
+ continue;
+ if (sb->s_op->write_super && sb->s_dirt) {
+ sb->s_count++;
+ spin_unlock(&sb_lock);
+
+ down_read(&sb->s_umount);
+ if (sb->s_root && sb->s_dirt && (sb->s_flags & MS_BORN))
+ sb->s_op->write_super(sb);
+ up_read(&sb->s_umount);
+
+ spin_lock(&sb_lock);
+ if (p)
+ __put_super(p);
+ p = sb;
+ }
+ }
+ if (p)
+ __put_super(p);
+ spin_unlock(&sb_lock);
+}
+
+/**
+ * iterate_supers - call function for all active superblocks
+ * @f: function to call
+ * @arg: argument to pass to it
+ *
+ * Scans the superblock list and calls given function, passing it
+ * locked superblock and given argument.
+ */
+void iterate_supers(void (*f)(struct super_block *, void *), void *arg)
+{
+ struct super_block *sb, *p = NULL;
+
+ spin_lock(&sb_lock);
+ list_for_each_entry(sb, &super_blocks, s_list) {
+ if (hlist_unhashed(&sb->s_instances))
+ continue;
+ sb->s_count++;
+ spin_unlock(&sb_lock);
+
+ down_read(&sb->s_umount);
+ if (sb->s_root && (sb->s_flags & MS_BORN))
+ f(sb, arg);
+ up_read(&sb->s_umount);
+
+ spin_lock(&sb_lock);
+ if (p)
+ __put_super(p);
+ p = sb;
+ }
+ if (p)
+ __put_super(p);
+ spin_unlock(&sb_lock);
+}
+
+/**
+ * iterate_supers_type - call function for superblocks of given type
+ * @type: fs type
+ * @f: function to call
+ * @arg: argument to pass to it
+ *
+ * Scans the superblock list and calls given function, passing it
+ * locked superblock and given argument.
+ */
+void iterate_supers_type(struct file_system_type *type,
+ void (*f)(struct super_block *, void *), void *arg)
+{
+ struct super_block *sb, *p = NULL;
+ struct hlist_node *node;
+
+ spin_lock(&sb_lock);
+ hlist_for_each_entry(sb, node, &type->fs_supers, s_instances) {
+ sb->s_count++;
+ spin_unlock(&sb_lock);
+
+ down_read(&sb->s_umount);
+ if (sb->s_root && (sb->s_flags & MS_BORN))
+ f(sb, arg);
+ up_read(&sb->s_umount);
+
+ spin_lock(&sb_lock);
+ if (p)
+ __put_super(p);
+ p = sb;
+ }
+ if (p)
+ __put_super(p);
+ spin_unlock(&sb_lock);
+}
+
+EXPORT_SYMBOL(iterate_supers_type);
+
+/**
+ * get_super - get the superblock of a device
+ * @bdev: device to get the superblock for
+ *
+ * Scans the superblock list and finds the superblock of the file system
+ * mounted on the device given. %NULL is returned if no match is found.
+ */
+
+struct super_block *get_super(struct block_device *bdev)
+{
+ struct super_block *sb;
+
+ if (!bdev)
+ return NULL;
+
+ spin_lock(&sb_lock);
+rescan:
+ list_for_each_entry(sb, &super_blocks, s_list) {
+ if (hlist_unhashed(&sb->s_instances))
+ continue;
+ if (sb->s_bdev == bdev) {
+ sb->s_count++;
+ spin_unlock(&sb_lock);
+ down_read(&sb->s_umount);
+ /* still alive? */
+ if (sb->s_root && (sb->s_flags & MS_BORN))
+ return sb;
+ up_read(&sb->s_umount);
+ /* nope, got unmounted */
+ spin_lock(&sb_lock);
+ __put_super(sb);
+ goto rescan;
+ }
+ }
+ spin_unlock(&sb_lock);
+ return NULL;
+}
+
+EXPORT_SYMBOL(get_super);
+
+/**
+ * get_super_thawed - get thawed superblock of a device
+ * @bdev: device to get the superblock for
+ *
+ * Scans the superblock list and finds the superblock of the file system
+ * mounted on the device. The superblock is returned once it is thawed
+ * (or immediately if it was not frozen). %NULL is returned if no match
+ * is found.
+ */
+struct super_block *get_super_thawed(struct block_device *bdev)
+{
+ while (1) {
+ struct super_block *s = get_super(bdev);
+ if (!s || s->s_frozen == SB_UNFROZEN)
+ return s;
+ up_read(&s->s_umount);
+ vfs_check_frozen(s, SB_FREEZE_WRITE);
+ put_super(s);
+ }
+}
+EXPORT_SYMBOL(get_super_thawed);
+
+/**
+ * get_active_super - get an active reference to the superblock of a device
+ * @bdev: device to get the superblock for
+ *
+ * Scans the superblock list and finds the superblock of the file system
+ * mounted on the device given. Returns the superblock with an active
+ * reference or %NULL if none was found.
+ */
+struct super_block *get_active_super(struct block_device *bdev)
+{
+ struct super_block *sb;
+
+ if (!bdev)
+ return NULL;
+
+restart:
+ spin_lock(&sb_lock);
+ list_for_each_entry(sb, &super_blocks, s_list) {
+ if (hlist_unhashed(&sb->s_instances))
+ continue;
+ if (sb->s_bdev == bdev) {
+ if (!grab_super(sb))
+ goto restart;
+ up_write(&sb->s_umount);
+ return sb;
+ }
+ }
+ spin_unlock(&sb_lock);
+ return NULL;
+}
+
+struct super_block *user_get_super(dev_t dev)
+{
+ struct super_block *sb;
+
+ spin_lock(&sb_lock);
+rescan:
+ list_for_each_entry(sb, &super_blocks, s_list) {
+ if (hlist_unhashed(&sb->s_instances))
+ continue;
+ if (sb->s_dev == dev) {
+ sb->s_count++;
+ spin_unlock(&sb_lock);
+ down_read(&sb->s_umount);
+ /* still alive? */
+ if (sb->s_root && (sb->s_flags & MS_BORN))
+ return sb;
+ up_read(&sb->s_umount);
+ /* nope, got unmounted */
+ spin_lock(&sb_lock);
+ __put_super(sb);
+ goto rescan;
+ }
+ }
+ spin_unlock(&sb_lock);
+ return NULL;
+}
+
+/**
+ * do_remount_sb - asks filesystem to change mount options.
+ * @sb: superblock in question
+ * @flags: numeric part of options
+ * @data: the rest of options
+ * @force: whether or not to force the change
+ *
+ * Alters the mount options of a mounted file system.
+ */
+int do_remount_sb(struct super_block *sb, int flags, void *data, int force)
+{
+ int retval;
+ int remount_ro;
+
+ if (sb->s_frozen != SB_UNFROZEN)
+ return -EBUSY;
+
+#ifdef CONFIG_BLOCK
+ if (!(flags & MS_RDONLY) && bdev_read_only(sb->s_bdev))
+ return -EACCES;
+#endif
+
+ if (flags & MS_RDONLY)
+ acct_auto_close(sb);
+ shrink_dcache_sb(sb);
+ sync_filesystem(sb);
+
+ remount_ro = (flags & MS_RDONLY) && !(sb->s_flags & MS_RDONLY);
+
+ /* If we are remounting RDONLY and current sb is read/write,
+ make sure there are no rw files opened */
+ if (remount_ro) {
+ if (force) {
+ mark_files_ro(sb);
+ } else {
+ retval = sb_prepare_remount_readonly(sb);
+ if (retval)
+ return retval;
+ }
+ }
+
+ if (sb->s_op->remount_fs) {
+ retval = sb->s_op->remount_fs(sb, &flags, data);
+ if (retval) {
+ if (!force)
+ goto cancel_readonly;
+ /* If forced remount, go ahead despite any errors */
+ WARN(1, "forced remount of a %s fs returned %i\n",
+ sb->s_type->name, retval);
+ }
+ }
+ sb->s_flags = (sb->s_flags & ~MS_RMT_MASK) | (flags & MS_RMT_MASK);
+ /* Needs to be ordered wrt mnt_is_readonly() */
+ smp_wmb();
+ sb->s_readonly_remount = 0;
+
+ /*
+ * Some filesystems modify their metadata via some other path than the
+ * bdev buffer cache (eg. use a private mapping, or directories in
+ * pagecache, etc). Also file data modifications go via their own
+ * mappings. So If we try to mount readonly then copy the filesystem
+ * from bdev, we could get stale data, so invalidate it to give a best
+ * effort at coherency.
+ */
+ if (remount_ro && sb->s_bdev)
+ invalidate_bdev(sb->s_bdev);
+ return 0;
+
+cancel_readonly:
+ sb->s_readonly_remount = 0;
+ return retval;
+}
+
+static void do_emergency_remount(struct work_struct *work)
+{
+ struct super_block *sb, *p = NULL;
+
+ spin_lock(&sb_lock);
+ list_for_each_entry(sb, &super_blocks, s_list) {
+ if (hlist_unhashed(&sb->s_instances))
+ continue;
+ sb->s_count++;
+ spin_unlock(&sb_lock);
+ down_write(&sb->s_umount);
+ if (sb->s_root && sb->s_bdev && (sb->s_flags & MS_BORN) &&
+ !(sb->s_flags & MS_RDONLY)) {
+ /*
+ * What lock protects sb->s_flags??
+ */
+ do_remount_sb(sb, MS_RDONLY, NULL, 1);
+ }
+ up_write(&sb->s_umount);
+ spin_lock(&sb_lock);
+ if (p)
+ __put_super(p);
+ p = sb;
+ }
+ if (p)
+ __put_super(p);
+ spin_unlock(&sb_lock);
+ kfree(work);
+ printk("Emergency Remount complete\n");
+}
+
+void emergency_remount(void)
+{
+ struct work_struct *work;
+
+ work = kmalloc(sizeof(*work), GFP_ATOMIC);
+ if (work) {
+ INIT_WORK(work, do_emergency_remount);
+ schedule_work(work);
+ }
+}
+
+/*
+ * Unnamed block devices are dummy devices used by virtual
+ * filesystems which don't use real block-devices. -- jrs
+ */
+
+static DEFINE_IDA(unnamed_dev_ida);
+static DEFINE_SPINLOCK(unnamed_dev_lock);/* protects the above */
+static int unnamed_dev_start = 0; /* don't bother trying below it */
+
+int get_anon_bdev(dev_t *p)
+{
+ int dev;
+ int error;
+
+ retry:
+ if (ida_pre_get(&unnamed_dev_ida, GFP_ATOMIC) == 0)
+ return -ENOMEM;
+ spin_lock(&unnamed_dev_lock);
+ error = ida_get_new_above(&unnamed_dev_ida, unnamed_dev_start, &dev);
+ if (!error)
+ unnamed_dev_start = dev + 1;
+ spin_unlock(&unnamed_dev_lock);
+ if (error == -EAGAIN)
+ /* We raced and lost with another CPU. */
+ goto retry;
+ else if (error)
+ return -EAGAIN;
+
+ if ((dev & MAX_ID_MASK) == (1 << MINORBITS)) {
+ spin_lock(&unnamed_dev_lock);
+ ida_remove(&unnamed_dev_ida, dev);
+ if (unnamed_dev_start > dev)
+ unnamed_dev_start = dev;
+ spin_unlock(&unnamed_dev_lock);
+ return -EMFILE;
+ }
+ *p = MKDEV(0, dev & MINORMASK);
+ return 0;
+}
+EXPORT_SYMBOL(get_anon_bdev);
+
+void free_anon_bdev(dev_t dev)
+{
+ int slot = MINOR(dev);
+ spin_lock(&unnamed_dev_lock);
+ ida_remove(&unnamed_dev_ida, slot);
+ if (slot < unnamed_dev_start)
+ unnamed_dev_start = slot;
+ spin_unlock(&unnamed_dev_lock);
+}
+EXPORT_SYMBOL(free_anon_bdev);
+
+int set_anon_super(struct super_block *s, void *data)
+{
+ int error = get_anon_bdev(&s->s_dev);
+ if (!error)
+ s->s_bdi = &noop_backing_dev_info;
+ return error;
+}
+
+EXPORT_SYMBOL(set_anon_super);
+
+void kill_anon_super(struct super_block *sb)
+{
+ dev_t dev = sb->s_dev;
+ generic_shutdown_super(sb);
+ free_anon_bdev(dev);
+}
+
+EXPORT_SYMBOL(kill_anon_super);
+
+void kill_litter_super(struct super_block *sb)
+{
+ if (sb->s_root)
+ d_genocide(sb->s_root);
+ kill_anon_super(sb);
+}
+
+EXPORT_SYMBOL(kill_litter_super);
+
+static int ns_test_super(struct super_block *sb, void *data)
+{
+ return sb->s_fs_info == data;
+}
+
+static int ns_set_super(struct super_block *sb, void *data)
+{
+ sb->s_fs_info = data;
+ return set_anon_super(sb, NULL);
+}
+
+struct dentry *mount_ns(struct file_system_type *fs_type, int flags,
+ void *data, int (*fill_super)(struct super_block *, void *, int))
+{
+ struct super_block *sb;
+
+ sb = sget(fs_type, ns_test_super, ns_set_super, data);
+ if (IS_ERR(sb))
+ return ERR_CAST(sb);
+
+ if (!sb->s_root) {
+ int err;
+ sb->s_flags = flags;
+ err = fill_super(sb, data, flags & MS_SILENT ? 1 : 0);
+ if (err) {
+ deactivate_locked_super(sb);
+ return ERR_PTR(err);
+ }
+
+ sb->s_flags |= MS_ACTIVE;
+ }
+
+ return dget(sb->s_root);
+}
+
+EXPORT_SYMBOL(mount_ns);
+
+#ifdef CONFIG_BLOCK
+static int set_bdev_super(struct super_block *s, void *data)
+{
+ s->s_bdev = data;
+ s->s_dev = s->s_bdev->bd_dev;
+
+ /*
+ * We set the bdi here to the queue backing, file systems can
+ * overwrite this in ->fill_super()
+ */
+ s->s_bdi = &bdev_get_queue(s->s_bdev)->backing_dev_info;
+ return 0;
+}
+
+static int test_bdev_super(struct super_block *s, void *data)
+{
+ return (void *)s->s_bdev == data;
+}
+
+struct dentry *mount_bdev(struct file_system_type *fs_type,
+ int flags, const char *dev_name, void *data,
+ int (*fill_super)(struct super_block *, void *, int))
+{
+ struct block_device *bdev;
+ struct super_block *s;
+ fmode_t mode = FMODE_READ | FMODE_EXCL;
+ int error = 0;
+
+ if (!(flags & MS_RDONLY))
+ mode |= FMODE_WRITE;
+
+ bdev = blkdev_get_by_path(dev_name, mode, fs_type);
+ if (IS_ERR(bdev))
+ return ERR_CAST(bdev);
+
+ /*
+ * once the super is inserted into the list by sget, s_umount
+ * will protect the lockfs code from trying to start a snapshot
+ * while we are mounting
+ */
+ mutex_lock(&bdev->bd_fsfreeze_mutex);
+ if (bdev->bd_fsfreeze_count > 0) {
+ mutex_unlock(&bdev->bd_fsfreeze_mutex);
+ error = -EBUSY;
+ goto error_bdev;
+ }
+ s = sget(fs_type, test_bdev_super, set_bdev_super, bdev);
+ mutex_unlock(&bdev->bd_fsfreeze_mutex);
+ if (IS_ERR(s))
+ goto error_s;
+
+ if (s->s_root) {
+ if ((flags ^ s->s_flags) & MS_RDONLY) {
+ deactivate_locked_super(s);
+ error = -EBUSY;
+ goto error_bdev;
+ }
+
+ /*
+ * s_umount nests inside bd_mutex during
+ * __invalidate_device(). blkdev_put() acquires
+ * bd_mutex and can't be called under s_umount. Drop
+ * s_umount temporarily. This is safe as we're
+ * holding an active reference.
+ */
+ up_write(&s->s_umount);
+ blkdev_put(bdev, mode);
+ down_write(&s->s_umount);
+ } else {
+ char b[BDEVNAME_SIZE];
+
+ s->s_flags = flags | MS_NOSEC;
+ s->s_mode = mode;
+ strlcpy(s->s_id, bdevname(bdev, b), sizeof(s->s_id));
+ sb_set_blocksize(s, block_size(bdev));
+ error = fill_super(s, data, flags & MS_SILENT ? 1 : 0);
+ if (error) {
+ deactivate_locked_super(s);
+ goto error;
+ }
+
+ s->s_flags |= MS_ACTIVE;
+ bdev->bd_super = s;
+ }
+
+ return dget(s->s_root);
+
+error_s:
+ error = PTR_ERR(s);
+error_bdev:
+ blkdev_put(bdev, mode);
+error:
+ return ERR_PTR(error);
+}
+EXPORT_SYMBOL(mount_bdev);
+
+void kill_block_super(struct super_block *sb)
+{
+ struct block_device *bdev = sb->s_bdev;
+ fmode_t mode = sb->s_mode;
+
+ bdev->bd_super = NULL;
+ generic_shutdown_super(sb);
+ sync_blockdev(bdev);
+ WARN_ON_ONCE(!(mode & FMODE_EXCL));
+ blkdev_put(bdev, mode | FMODE_EXCL);
+}
+
+EXPORT_SYMBOL(kill_block_super);
+#endif
+
+struct dentry *mount_nodev(struct file_system_type *fs_type,
+ int flags, void *data,
+ int (*fill_super)(struct super_block *, void *, int))
+{
+ int error;
+ struct super_block *s = sget(fs_type, NULL, set_anon_super, NULL);
+
+ if (IS_ERR(s))
+ return ERR_CAST(s);
+
+ s->s_flags = flags;
+
+ error = fill_super(s, data, flags & MS_SILENT ? 1 : 0);
+ if (error) {
+ deactivate_locked_super(s);
+ return ERR_PTR(error);
+ }
+ s->s_flags |= MS_ACTIVE;
+ return dget(s->s_root);
+}
+EXPORT_SYMBOL(mount_nodev);
+
+static int compare_single(struct super_block *s, void *p)
+{
+ return 1;
+}
+
+struct dentry *mount_single(struct file_system_type *fs_type,
+ int flags, void *data,
+ int (*fill_super)(struct super_block *, void *, int))
+{
+ struct super_block *s;
+ int error;
+
+ s = sget(fs_type, compare_single, set_anon_super, NULL);
+ if (IS_ERR(s))
+ return ERR_CAST(s);
+ if (!s->s_root) {
+ s->s_flags = flags;
+ error = fill_super(s, data, flags & MS_SILENT ? 1 : 0);
+ if (error) {
+ deactivate_locked_super(s);
+ return ERR_PTR(error);
+ }
+ s->s_flags |= MS_ACTIVE;
+ } else {
+ do_remount_sb(s, flags, data, 0);
+ }
+ 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)
+{
+ struct dentry *root;
+ struct super_block *sb;
+ char *secdata = NULL;
+ int error = -ENOMEM;
+
+ if (data && !(type->fs_flags & FS_BINARY_MOUNTDATA)) {
+ secdata = alloc_secdata();
+ if (!secdata)
+ goto out;
+
+ error = security_sb_copy_data(data, secdata);
+ if (error)
+ goto out_free_secdata;
+ }
+
+ root = type->mount(type, flags, name, data);
+ if (IS_ERR(root)) {
+ error = PTR_ERR(root);
+ goto out_free_secdata;
+ }
+ sb = root->d_sb;
+ BUG_ON(!sb);
+ WARN_ON(!sb->s_bdi);
+ WARN_ON(sb->s_bdi == &default_backing_dev_info);
+ sb->s_flags |= MS_BORN;
+
+ error = security_sb_kern_mount(sb, flags, secdata);
+ if (error)
+ goto out_sb;
+
+ /*
+ * filesystems should never set s_maxbytes larger than MAX_LFS_FILESIZE
+ * but s_maxbytes was an unsigned long long for many releases. Throw
+ * this warning for a little while to try and catch filesystems that
+ * violate this rule.
+ */
+ WARN((sb->s_maxbytes < 0), "%s set sb->s_maxbytes to "
+ "negative value (%lld)\n", type->name, sb->s_maxbytes);
+
+ up_write(&sb->s_umount);
+ free_secdata(secdata);
+ return root;
+out_sb:
+ dput(root);
+ deactivate_locked_super(sb);
+out_free_secdata:
+ free_secdata(secdata);
+out:
+ return ERR_PTR(error);
+}
+
+/**
+ * freeze_super - lock the filesystem and force it into a consistent state
+ * @sb: the super to lock
+ *
+ * Syncs the super to make sure the filesystem is consistent and calls the fs's
+ * freeze_fs. Subsequent calls to this without first thawing the fs will return
+ * -EBUSY.
+ */
+int freeze_super(struct super_block *sb)
+{
+ int ret;
+
+ atomic_inc(&sb->s_active);
+ down_write(&sb->s_umount);
+ if (sb->s_frozen) {
+ deactivate_locked_super(sb);
+ return -EBUSY;
+ }
+
+ if (!(sb->s_flags & MS_BORN)) {
+ up_write(&sb->s_umount);
+ return 0; /* sic - it's "nothing to do" */
+ }
+
+ if (sb->s_flags & MS_RDONLY) {
+ sb->s_frozen = SB_FREEZE_TRANS;
+ smp_wmb();
+ up_write(&sb->s_umount);
+ return 0;
+ }
+
+ sb->s_frozen = SB_FREEZE_WRITE;
+ smp_wmb();
+
+ sync_filesystem(sb);
+
+ sb->s_frozen = SB_FREEZE_TRANS;
+ smp_wmb();
+
+ sync_blockdev(sb->s_bdev);
+ if (sb->s_op->freeze_fs) {
+ ret = sb->s_op->freeze_fs(sb);
+ if (ret) {
+ printk(KERN_ERR
+ "VFS:Filesystem freeze failed\n");
+ sb->s_frozen = SB_UNFROZEN;
+ smp_wmb();
+ wake_up(&sb->s_wait_unfrozen);
+ deactivate_locked_super(sb);
+ return ret;
+ }
+ }
+ up_write(&sb->s_umount);
+ return 0;
+}
+EXPORT_SYMBOL(freeze_super);
+
+/**
+ * thaw_super -- unlock filesystem
+ * @sb: the super to thaw
+ *
+ * Unlocks the filesystem and marks it writeable again after freeze_super().
+ */
+int thaw_super(struct super_block *sb)
+{
+ int error;
+
+ down_write(&sb->s_umount);
+ if (sb->s_frozen == SB_UNFROZEN) {
+ up_write(&sb->s_umount);
+ return -EINVAL;
+ }
+
+ if (sb->s_flags & MS_RDONLY)
+ goto out;
+
+ if (sb->s_op->unfreeze_fs) {
+ error = sb->s_op->unfreeze_fs(sb);
+ if (error) {
+ printk(KERN_ERR
+ "VFS:Filesystem thaw failed\n");
+ sb->s_frozen = SB_FREEZE_TRANS;
+ up_write(&sb->s_umount);
+ return error;
+ }
+ }
+
+out:
+ sb->s_frozen = SB_UNFROZEN;
+ smp_wmb();
+ wake_up(&sb->s_wait_unfrozen);
+ deactivate_locked_super(sb);
+
+ return 0;
+}
+EXPORT_SYMBOL(thaw_super);