Merge git://git.kernel.org/pub/scm/linux/kernel/git/mason/btrfs-unstable

* git://git.kernel.org/pub/scm/linux/kernel/git/mason/btrfs-unstable: (24 commits)
  Btrfs: don't use migrate page without CONFIG_MIGRATION
  Btrfs: deal with DIO bios that span more than one ordered extent
  Btrfs: setup blank root and fs_info for mount time
  Btrfs: fix fiemap
  Btrfs - fix race between btrfs_get_sb() and umount
  Btrfs: update inode ctime when using links
  Btrfs: make sure new inode size is ok in fallocate
  Btrfs: fix typo in fallocate to make it honor actual size
  Btrfs: avoid NULL pointer deref in try_release_extent_buffer
  Btrfs: make btrfs_add_nondir take parent inode as an argument
  Btrfs: hold i_mutex when calling btrfs_log_dentry_safe
  Btrfs: use dget_parent where we can UPDATED
  Btrfs: fix more ESTALE problems with NFS
  Btrfs: handle NFS lookups properly
  btrfs: make 1-bit signed fileds unsigned
  btrfs: Show device attr correctly for symlinks
  btrfs: Set file size correctly in file clone
  btrfs: Check if dest_offset is block-size aligned before cloning file
  Btrfs: handle the space_cache option properly
  btrfs: Fix early enospc because 'unused' calculated with wrong sign.
  ...

fs/btrfs/compression.c

@@ -91,23 +91,10 @@ static inline int compressed_bio_size(struct btrfs_root *root,
 static struct bio *compressed_bio_alloc(struct block_device *bdev,
 					u64 first_byte, gfp_t gfp_flags)
 {
-	struct bio *bio;
 	int nr_vecs;
 
 	nr_vecs = bio_get_nr_vecs(bdev);
-	bio = bio_alloc(gfp_flags, nr_vecs);
-
-	if (bio == NULL && (current->flags & PF_MEMALLOC)) {
-		while (!bio && (nr_vecs /= 2))
-			bio = bio_alloc(gfp_flags, nr_vecs);
-	}
-
-	if (bio) {
-		bio->bi_size = 0;
-		bio->bi_bdev = bdev;
-		bio->bi_sector = first_byte >> 9;
-	}
-	return bio;
+	return btrfs_bio_alloc(bdev, first_byte >> 9, nr_vecs, gfp_flags);
 }
 
 static int check_compressed_csum(struct inode *inode,

fs/btrfs/ctree.h

@@ -808,9 +808,9 @@ struct btrfs_block_group_cache {
 	int extents_thresh;
 	int free_extents;
 	int total_bitmaps;
-	int ro:1;
-	int dirty:1;
-	int iref:1;
+	unsigned int ro:1;
+	unsigned int dirty:1;
+	unsigned int iref:1;
 
 	int disk_cache_state;
 

fs/btrfs/disk-io.c

@@ -28,6 +28,7 @@
 #include <linux/freezer.h>
 #include <linux/crc32c.h>
 #include <linux/slab.h>
+#include <linux/migrate.h>
 #include "compat.h"
 #include "ctree.h"
 #include "disk-io.h"
@@ -355,6 +356,8 @@ static int csum_dirty_buffer(struct btrfs_root *root, struct page *page)
 	ret = btree_read_extent_buffer_pages(root, eb, start + PAGE_CACHE_SIZE,
 					     btrfs_header_generation(eb));
 	BUG_ON(ret);
+	WARN_ON(!btrfs_header_flag(eb, BTRFS_HEADER_FLAG_WRITTEN));
+
 	found_start = btrfs_header_bytenr(eb);
 	if (found_start != start) {
 		WARN_ON(1);
@@ -693,6 +696,29 @@ static int btree_submit_bio_hook(struct inode *inode, int rw, struct bio *bio,
 				   __btree_submit_bio_done);
 }
 
+static int btree_migratepage(struct address_space *mapping,
+			struct page *newpage, struct page *page)
+{
+	/*
+	 * we can't safely write a btree page from here,
+	 * we haven't done the locking hook
+	 */
+	if (PageDirty(page))
+		return -EAGAIN;
+	/*
+	 * Buffers may be managed in a filesystem specific way.
+	 * We must have no buffers or drop them.
+	 */
+	if (page_has_private(page) &&
+	    !try_to_release_page(page, GFP_KERNEL))
+		return -EAGAIN;
+#ifdef CONFIG_MIGRATION
+	return migrate_page(mapping, newpage, page);
+#else
+	return -ENOSYS;
+#endif
+}
+
 static int btree_writepage(struct page *page, struct writeback_control *wbc)
 {
 	struct extent_io_tree *tree;
@@ -707,8 +733,7 @@ static int btree_writepage(struct page *page, struct writeback_control *wbc)
 	}
 
 	redirty_page_for_writepage(wbc, page);
-	eb = btrfs_find_tree_block(root, page_offset(page),
-				      PAGE_CACHE_SIZE);
+	eb = btrfs_find_tree_block(root, page_offset(page), PAGE_CACHE_SIZE);
 	WARN_ON(!eb);
 
 	was_dirty = test_and_set_bit(EXTENT_BUFFER_DIRTY, &eb->bflags);
@@ -799,6 +824,9 @@ static const struct address_space_operations btree_aops = {
 	.releasepage	= btree_releasepage,
 	.invalidatepage = btree_invalidatepage,
 	.sync_page	= block_sync_page,
+#ifdef CONFIG_MIGRATION
+	.migratepage	= btree_migratepage,
+#endif
 };
 
 int readahead_tree_block(struct btrfs_root *root, u64 bytenr, u32 blocksize,
@@ -1538,10 +1566,8 @@ struct btrfs_root *open_ctree(struct super_block *sb,
 						 GFP_NOFS);
 	struct btrfs_root *csum_root = kzalloc(sizeof(struct btrfs_root),
 						 GFP_NOFS);
-	struct btrfs_root *tree_root = kzalloc(sizeof(struct btrfs_root),
-					       GFP_NOFS);
-	struct btrfs_fs_info *fs_info = kzalloc(sizeof(*fs_info),
-						GFP_NOFS);
+	struct btrfs_root *tree_root = btrfs_sb(sb);
+	struct btrfs_fs_info *fs_info = tree_root->fs_info;
 	struct btrfs_root *chunk_root = kzalloc(sizeof(struct btrfs_root),
 						GFP_NOFS);
 	struct btrfs_root *dev_root = kzalloc(sizeof(struct btrfs_root),

fs/btrfs/export.c

@@ -232,9 +232,85 @@ static struct dentry *btrfs_get_parent(struct dentry *child)
 	return ERR_PTR(ret);
 }
 
+static int btrfs_get_name(struct dentry *parent, char *name,
+			  struct dentry *child)
+{
+	struct inode *inode = child->d_inode;
+	struct inode *dir = parent->d_inode;
+	struct btrfs_path *path;
+	struct btrfs_root *root = BTRFS_I(dir)->root;
+	struct btrfs_inode_ref *iref;
+	struct btrfs_root_ref *rref;
+	struct extent_buffer *leaf;
+	unsigned long name_ptr;
+	struct btrfs_key key;
+	int name_len;
+	int ret;
+
+	if (!dir || !inode)
+		return -EINVAL;
+
+	if (!S_ISDIR(dir->i_mode))
+		return -EINVAL;
+
+	path = btrfs_alloc_path();
+	if (!path)
+		return -ENOMEM;
+	path->leave_spinning = 1;
+
+	if (inode->i_ino == BTRFS_FIRST_FREE_OBJECTID) {
+		key.objectid = BTRFS_I(inode)->root->root_key.objectid;
+		key.type = BTRFS_ROOT_BACKREF_KEY;
+		key.offset = (u64)-1;
+		root = root->fs_info->tree_root;
+	} else {
+		key.objectid = inode->i_ino;
+		key.offset = dir->i_ino;
+		key.type = BTRFS_INODE_REF_KEY;
+	}
+
+	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
+	if (ret < 0) {
+		btrfs_free_path(path);
+		return ret;
+	} else if (ret > 0) {
+		if (inode->i_ino == BTRFS_FIRST_FREE_OBJECTID) {
+			path->slots[0]--;
+		} else {
+			btrfs_free_path(path);
+			return -ENOENT;
+		}
+	}
+	leaf = path->nodes[0];
+
+	if (inode->i_ino == BTRFS_FIRST_FREE_OBJECTID) {
+	       rref = btrfs_item_ptr(leaf, path->slots[0],
+				     struct btrfs_root_ref);
+	       name_ptr = (unsigned long)(rref + 1);
+	       name_len = btrfs_root_ref_name_len(leaf, rref);
+	} else {
+		iref = btrfs_item_ptr(leaf, path->slots[0],
+				      struct btrfs_inode_ref);
+		name_ptr = (unsigned long)(iref + 1);
+		name_len = btrfs_inode_ref_name_len(leaf, iref);
+	}
+
+	read_extent_buffer(leaf, name, name_ptr, name_len);
+	btrfs_free_path(path);
+
+	/*
+	 * have to add the null termination to make sure that reconnect_path
+	 * gets the right len for strlen
+	 */
+	name[name_len] = '\0';
+
+	return 0;
+}
+
 const struct export_operations btrfs_export_ops = {
 	.encode_fh	= btrfs_encode_fh,
 	.fh_to_dentry	= btrfs_fh_to_dentry,
 	.fh_to_parent	= btrfs_fh_to_parent,
 	.get_parent	= btrfs_get_parent,
+	.get_name	= btrfs_get_name,
 };

fs/btrfs/extent-tree.c

@@ -3412,7 +3412,7 @@ static int reserve_metadata_bytes(struct btrfs_trans_handle *trans,
 	 * our reservation.
 	 */
 	if (unused <= space_info->total_bytes) {
-		unused -= space_info->total_bytes;
+		unused = space_info->total_bytes - unused;
 		if (unused >= num_bytes) {
 			if (!reserved)
 				space_info->bytes_reserved += orig_bytes;

fs/btrfs/extent_io.c

@@ -1828,8 +1828,8 @@ static void end_bio_extent_preparewrite(struct bio *bio, int err)
 	bio_put(bio);
 }
 
-static struct bio *
-extent_bio_alloc(struct block_device *bdev, u64 first_sector, int nr_vecs,
+struct bio *
+btrfs_bio_alloc(struct block_device *bdev, u64 first_sector, int nr_vecs,
 		gfp_t gfp_flags)
 {
 	struct bio *bio;
@@ -1919,7 +1919,7 @@ static int submit_extent_page(int rw, struct extent_io_tree *tree,
 	else
 		nr = bio_get_nr_vecs(bdev);
 
-	bio = extent_bio_alloc(bdev, sector, nr, GFP_NOFS | __GFP_HIGH);
+	bio = btrfs_bio_alloc(bdev, sector, nr, GFP_NOFS | __GFP_HIGH);
 
 	bio_add_page(bio, page, page_size, offset);
 	bio->bi_end_io = end_io_func;
@@ -2901,21 +2901,53 @@ sector_t extent_bmap(struct address_space *mapping, sector_t iblock,
 int extent_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
 		__u64 start, __u64 len, get_extent_t *get_extent)
 {
-	int ret;
+	int ret = 0;
 	u64 off = start;
 	u64 max = start + len;
 	u32 flags = 0;
+	u32 found_type;
+	u64 last;
 	u64 disko = 0;
+	struct btrfs_key found_key;
 	struct extent_map *em = NULL;
 	struct extent_state *cached_state = NULL;
+	struct btrfs_path *path;
+	struct btrfs_file_extent_item *item;
 	int end = 0;
 	u64 em_start = 0, em_len = 0;
 	unsigned long emflags;
-	ret = 0;
+	int hole = 0;
 
 	if (len == 0)
 		return -EINVAL;
 
+	path = btrfs_alloc_path();
+	if (!path)
+		return -ENOMEM;
+	path->leave_spinning = 1;
+
+	ret = btrfs_lookup_file_extent(NULL, BTRFS_I(inode)->root,
+				       path, inode->i_ino, -1, 0);
+	if (ret < 0) {
+		btrfs_free_path(path);
+		return ret;
+	}
+	WARN_ON(!ret);
+	path->slots[0]--;
+	item = btrfs_item_ptr(path->nodes[0], path->slots[0],
+			      struct btrfs_file_extent_item);
+	btrfs_item_key_to_cpu(path->nodes[0], &found_key, path->slots[0]);
+	found_type = btrfs_key_type(&found_key);
+
+	/* No extents, just return */
+	if (found_key.objectid != inode->i_ino ||
+	    found_type != BTRFS_EXTENT_DATA_KEY) {
+		btrfs_free_path(path);
+		return 0;
+	}
+	last = found_key.offset;
+	btrfs_free_path(path);
+
 	lock_extent_bits(&BTRFS_I(inode)->io_tree, start, start + len, 0,
 			 &cached_state, GFP_NOFS);
 	em = get_extent(inode, NULL, 0, off, max - off, 0);
@@ -2925,11 +2957,18 @@ int extent_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
 		ret = PTR_ERR(em);
 		goto out;
 	}
+
 	while (!end) {
+		hole = 0;
 		off = em->start + em->len;
 		if (off >= max)
 			end = 1;
 
+		if (em->block_start == EXTENT_MAP_HOLE) {
+			hole = 1;
+			goto next;
+		}
+
 		em_start = em->start;
 		em_len = em->len;
 
@@ -2939,8 +2978,6 @@ int extent_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
 		if (em->block_start == EXTENT_MAP_LAST_BYTE) {
 			end = 1;
 			flags |= FIEMAP_EXTENT_LAST;
-		} else if (em->block_start == EXTENT_MAP_HOLE) {
-			flags |= FIEMAP_EXTENT_UNWRITTEN;
 		} else if (em->block_start == EXTENT_MAP_INLINE) {
 			flags |= (FIEMAP_EXTENT_DATA_INLINE |
 				  FIEMAP_EXTENT_NOT_ALIGNED);
@@ -2953,10 +2990,10 @@ int extent_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
 		if (test_bit(EXTENT_FLAG_COMPRESSED, &em->flags))
 			flags |= FIEMAP_EXTENT_ENCODED;
 
+next:
 		emflags = em->flags;
 		free_extent_map(em);
 		em = NULL;
-
 		if (!end) {
 			em = get_extent(inode, NULL, 0, off, max - off, 0);
 			if (!em)
@@ -2967,16 +3004,24 @@ int extent_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
 			}
 			emflags = em->flags;
 		}
+
 		if (test_bit(EXTENT_FLAG_VACANCY, &emflags)) {
 			flags |= FIEMAP_EXTENT_LAST;
 			end = 1;
 		}
 
+		if (em_start == last) {
+			flags |= FIEMAP_EXTENT_LAST;
+			end = 1;
+		}
+
+		if (!hole) {
 			ret = fiemap_fill_next_extent(fieinfo, em_start, disko,
 						em_len, flags);
 			if (ret)
 				goto out_free;
 		}
+	}
 out_free:
 	free_extent_map(em);
 out:
@@ -3836,8 +3881,10 @@ int try_release_extent_buffer(struct extent_io_tree *tree, struct page *page)
 
 	spin_lock(&tree->buffer_lock);
 	eb = radix_tree_lookup(&tree->buffer, start >> PAGE_CACHE_SHIFT);
-	if (!eb)
-		goto out;
+	if (!eb) {
+		spin_unlock(&tree->buffer_lock);
+		return ret;
+	}
 
 	if (test_bit(EXTENT_BUFFER_DIRTY, &eb->bflags)) {
 		ret = 0;

fs/btrfs/extent_io.h

@@ -310,4 +310,7 @@ int extent_clear_unlock_delalloc(struct inode *inode,
 				struct extent_io_tree *tree,
 				u64 start, u64 end, struct page *locked_page,
 				unsigned long op);
+struct bio *
+btrfs_bio_alloc(struct block_device *bdev, u64 first_sector, int nr_vecs,
+		gfp_t gfp_flags);
 #endif

fs/btrfs/file.c

@@ -1047,8 +1047,14 @@ static ssize_t btrfs_file_aio_write(struct kiocb *iocb,
 
 		if ((file->f_flags & O_DSYNC) || IS_SYNC(inode)) {
 			trans = btrfs_start_transaction(root, 0);
+			if (IS_ERR(trans)) {
+				num_written = PTR_ERR(trans);
+				goto done;
+			}
+			mutex_lock(&inode->i_mutex);
 			ret = btrfs_log_dentry_safe(trans, root,
 						    file->f_dentry);
+			mutex_unlock(&inode->i_mutex);
 			if (ret == 0) {
 				ret = btrfs_sync_log(trans, root);
 				if (ret == 0)
@@ -1067,6 +1073,7 @@ static ssize_t btrfs_file_aio_write(struct kiocb *iocb,
 			     (start_pos + num_written - 1) >> PAGE_CACHE_SHIFT);
 		}
 	}
+done:
 	current->backing_dev_info = NULL;
 	return num_written ? num_written : err;
 }

fs/btrfs/ioctl.c

@@ -233,7 +233,8 @@ static noinline int create_subvol(struct btrfs_root *root,
 	struct btrfs_inode_item *inode_item;
 	struct extent_buffer *leaf;
 	struct btrfs_root *new_root;
-	struct inode *dir = dentry->d_parent->d_inode;
+	struct dentry *parent = dget_parent(dentry);
+	struct inode *dir;
 	int ret;
 	int err;
 	u64 objectid;
@@ -242,8 +243,13 @@ static noinline int create_subvol(struct btrfs_root *root,
 
 	ret = btrfs_find_free_objectid(NULL, root->fs_info->tree_root,
 				       0, &objectid);
-	if (ret)
+	if (ret) {
+		dput(parent);
 		return ret;
+	}
+
+	dir = parent->d_inode;
+
 	/*
 	 * 1 - inode item
 	 * 2 - refs
@@ -251,8 +257,10 @@ static noinline int create_subvol(struct btrfs_root *root,
 	 * 2 - dir items
 	 */
 	trans = btrfs_start_transaction(root, 6);
-	if (IS_ERR(trans))
+	if (IS_ERR(trans)) {
+		dput(parent);
 		return PTR_ERR(trans);
+	}
 
 	leaf = btrfs_alloc_free_block(trans, root, root->leafsize,
 				      0, objectid, NULL, 0, 0, 0);
@@ -339,6 +347,7 @@ static noinline int create_subvol(struct btrfs_root *root,
 
 	d_instantiate(dentry, btrfs_lookup_dentry(dir, dentry));
 fail:
+	dput(parent);
 	if (async_transid) {
 		*async_transid = trans->transid;
 		err = btrfs_commit_transaction_async(trans, root, 1);
@@ -354,6 +363,7 @@ static int create_snapshot(struct btrfs_root *root, struct dentry *dentry,
 			   char *name, int namelen, u64 *async_transid)
 {
 	struct inode *inode;
+	struct dentry *parent;
 	struct btrfs_pending_snapshot *pending_snapshot;
 	struct btrfs_trans_handle *trans;
 	int ret;
@@ -396,7 +406,9 @@ static int create_snapshot(struct btrfs_root *root, struct dentry *dentry,
 
 	btrfs_orphan_cleanup(pending_snapshot->snap);
 
-	inode = btrfs_lookup_dentry(dentry->d_parent->d_inode, dentry);
+	parent = dget_parent(dentry);
+	inode = btrfs_lookup_dentry(parent->d_inode, dentry);
+	dput(parent);
 	if (IS_ERR(inode)) {
 		ret = PTR_ERR(inode);
 		goto fail;
@@ -1669,12 +1681,11 @@ static noinline long btrfs_ioctl_clone(struct file *file, unsigned long srcfd,
 		olen = len = src->i_size - off;
 	/* if we extend to eof, continue to block boundary */
 	if (off + len == src->i_size)
-		len = ((src->i_size + bs-1) & ~(bs-1))
-			- off;
+		len = ALIGN(src->i_size, bs) - off;
 
 	/* verify the end result is block aligned */
-	if ((off & (bs-1)) ||
-	    ((off + len) & (bs-1)))
+	if (!IS_ALIGNED(off, bs) || !IS_ALIGNED(off + len, bs) ||
+	    !IS_ALIGNED(destoff, bs))
 		goto out_unlock;
 
 	/* do any pending delalloc/csum calc on src, one way or
@@ -1874,8 +1885,8 @@ static noinline long btrfs_ioctl_clone(struct file *file, unsigned long srcfd,
 			 * but shouldn't round up the file size
 			 */
 			endoff = new_key.offset + datal;
-			if (endoff > off+olen)
-				endoff = off+olen;
+			if (endoff > destoff+olen)
+				endoff = destoff+olen;
 			if (endoff > inode->i_size)
 				btrfs_i_size_write(inode, endoff);
 

fs/btrfs/ordered-data.c

@@ -248,6 +248,73 @@ int btrfs_add_ordered_sum(struct inode *inode,
 	return 0;
 }
 
+/*
+ * this is used to account for finished IO across a given range
+ * of the file.  The IO may span ordered extents.  If
+ * a given ordered_extent is completely done, 1 is returned, otherwise
+ * 0.
+ *
+ * test_and_set_bit on a flag in the struct btrfs_ordered_extent is used
+ * to make sure this function only returns 1 once for a given ordered extent.
+ *
+ * file_offset is updated to one byte past the range that is recorded as
+ * complete.  This allows you to walk forward in the file.
+ */
+int btrfs_dec_test_first_ordered_pending(struct inode *inode,
+				   struct btrfs_ordered_extent **cached,
+				   u64 *file_offset, u64 io_size)
+{
+	struct btrfs_ordered_inode_tree *tree;
+	struct rb_node *node;
+	struct btrfs_ordered_extent *entry = NULL;
+	int ret;
+	u64 dec_end;
+	u64 dec_start;
+	u64 to_dec;
+
+	tree = &BTRFS_I(inode)->ordered_tree;
+	spin_lock(&tree->lock);
+	node = tree_search(tree, *file_offset);
+	if (!node) {
+		ret = 1;
+		goto out;
+	}
+
+	entry = rb_entry(node, struct btrfs_ordered_extent, rb_node);
+	if (!offset_in_entry(entry, *file_offset)) {
+		ret = 1;
+		goto out;
+	}
+
+	dec_start = max(*file_offset, entry->file_offset);
+	dec_end = min(*file_offset + io_size, entry->file_offset +
+		      entry->len);
+	*file_offset = dec_end;
+	if (dec_start > dec_end) {
+		printk(KERN_CRIT "bad ordering dec_start %llu end %llu\n",
+		       (unsigned long long)dec_start,
+		       (unsigned long long)dec_end);
+	}
+	to_dec = dec_end - dec_start;
+	if (to_dec > entry->bytes_left) {
+		printk(KERN_CRIT "bad ordered accounting left %llu size %llu\n",
+		       (unsigned long long)entry->bytes_left,
+		       (unsigned long long)to_dec);
+	}
+	entry->bytes_left -= to_dec;
+	if (entry->bytes_left == 0)
+		ret = test_and_set_bit(BTRFS_ORDERED_IO_DONE, &entry->flags);
+	else
+		ret = 1;
+out:
+	if (!ret && cached && entry) {
+		*cached = entry;
+		atomic_inc(&entry->refs);
+	}
+	spin_unlock(&tree->lock);
+	return ret == 0;
+}
+
 /*
  * this is used to account for finished IO across a given range
  * of the file.  The IO should not span ordered extents.  If

fs/btrfs/ordered-data.h

@@ -141,6 +141,9 @@ int btrfs_remove_ordered_extent(struct inode *inode,
 int btrfs_dec_test_ordered_pending(struct inode *inode,
 				   struct btrfs_ordered_extent **cached,
 				   u64 file_offset, u64 io_size);
+int btrfs_dec_test_first_ordered_pending(struct inode *inode,
+				   struct btrfs_ordered_extent **cached,
+				   u64 *file_offset, u64 io_size);
 int btrfs_add_ordered_extent(struct inode *inode, u64 file_offset,
 			     u64 start, u64 len, u64 disk_len, int type);
 int btrfs_add_ordered_extent_dio(struct inode *inode, u64 file_offset,

fs/btrfs/super.c

@@ -244,6 +244,7 @@ int btrfs_parse_options(struct btrfs_root *root, char *options)
 		case Opt_space_cache:
 			printk(KERN_INFO "btrfs: enabling disk space caching\n");
 			btrfs_set_opt(info->mount_opt, SPACE_CACHE);
+			break;
 		case Opt_clear_cache:
 			printk(KERN_INFO "btrfs: force clearing of disk cache\n");
 			btrfs_set_opt(info->mount_opt, CLEAR_CACHE);
@@ -562,12 +563,26 @@ static int btrfs_show_options(struct seq_file *seq, struct vfsmount *vfs)
 
 static int btrfs_test_super(struct super_block *s, void *data)
 {
-	struct btrfs_fs_devices *test_fs_devices = data;
+	struct btrfs_root *test_root = data;
 	struct btrfs_root *root = btrfs_sb(s);
 
-	return root->fs_info->fs_devices == test_fs_devices;
+	/*
+	 * If this super block is going away, return false as it
+	 * can't match as an existing super block.
+	 */
+	if (!atomic_read(&s->s_active))
+		return 0;
+	return root->fs_info->fs_devices == test_root->fs_info->fs_devices;
+}
+
+static int btrfs_set_super(struct super_block *s, void *data)
+{
+	s->s_fs_info = data;
+
+	return set_anon_super(s, data);
 }
 
+
 /*
  * Find a superblock for the given device / mount point.
  *
@@ -581,6 +596,8 @@ 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;
 	u64 subvol_objectid = 0;
@@ -608,8 +625,24 @@ static struct dentry *btrfs_mount(struct file_system_type *fs_type, int flags,
 		goto error_close_devices;
 	}
 
+	/*
+	 * Setup a dummy root and fs_info for test/set super.  This is because
+	 * we don't actually fill this stuff out until open_ctree, but we need
+	 * it for searching for existing supers, so this lets us do that and
+	 * 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) {
+		error = -ENOMEM;
+		goto error_close_devices;
+	}
+	fs_info->tree_root = tree_root;
+	fs_info->fs_devices = fs_devices;
+	tree_root->fs_info = fs_info;
+
 	bdev = fs_devices->latest_bdev;
-	s = sget(fs_type, btrfs_test_super, set_anon_super, fs_devices);
+	s = sget(fs_type, btrfs_test_super, btrfs_set_super, tree_root);
 	if (IS_ERR(s))
 		goto error_s;
 
@@ -675,6 +708,8 @@ static struct dentry *btrfs_mount(struct file_system_type *fs_type, int flags,
 	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);
 	return ERR_PTR(error);

fs/btrfs/transaction.c

@@ -902,6 +902,7 @@ static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
 	struct btrfs_root *root = pending->root;
 	struct btrfs_root *parent_root;
 	struct inode *parent_inode;
+	struct dentry *parent;
 	struct dentry *dentry;
 	struct extent_buffer *tmp;
 	struct extent_buffer *old;
@@ -941,7 +942,8 @@ static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
 	trans->block_rsv = &pending->block_rsv;
 
 	dentry = pending->dentry;
-	parent_inode = dentry->d_parent->d_inode;
+	parent = dget_parent(dentry);
+	parent_inode = parent->d_inode;
 	parent_root = BTRFS_I(parent_inode)->root;
 	record_root_in_trans(trans, parent_root);
 
@@ -989,6 +991,7 @@ static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
 				 parent_inode->i_ino, index,
 				 dentry->d_name.name, dentry->d_name.len);
 	BUG_ON(ret);
+	dput(parent);
 
 	key.offset = (u64)-1;
 	pending->snap = btrfs_read_fs_root_no_name(root->fs_info, &key);

fs/btrfs/tree-log.c

@@ -2869,6 +2869,7 @@ static noinline int check_parent_dirs_for_sync(struct btrfs_trans_handle *trans,
 {
 	int ret = 0;
 	struct btrfs_root *root;
+	struct dentry *old_parent = NULL;
 
 	/*
 	 * for regular files, if its inode is already on disk, we don't
@@ -2910,10 +2911,13 @@ static noinline int check_parent_dirs_for_sync(struct btrfs_trans_handle *trans,
 		if (IS_ROOT(parent))
 			break;
 
-		parent = parent->d_parent;
+		parent = dget_parent(parent);
+		dput(old_parent);
+		old_parent = parent;
 		inode = parent->d_inode;
 
 	}
+	dput(old_parent);
 out:
 	return ret;
 }
@@ -2945,6 +2949,7 @@ int btrfs_log_inode_parent(struct btrfs_trans_handle *trans,
 {
 	int inode_only = exists_only ? LOG_INODE_EXISTS : LOG_INODE_ALL;
 	struct super_block *sb;
+	struct dentry *old_parent = NULL;
 	int ret = 0;
 	u64 last_committed = root->fs_info->last_trans_committed;
 
@@ -3016,10 +3021,13 @@ int btrfs_log_inode_parent(struct btrfs_trans_handle *trans,
 		if (IS_ROOT(parent))
 			break;
 
-		parent = parent->d_parent;
+		parent = dget_parent(parent);
+		dput(old_parent);
+		old_parent = parent;
 	}
 	ret = 0;
 end_trans:
+	dput(old_parent);
 	if (ret < 0) {
 		BUG_ON(ret != -ENOSPC);
 		root->fs_info->last_trans_log_full_commit = trans->transid;
@@ -3039,8 +3047,13 @@ int btrfs_log_inode_parent(struct btrfs_trans_handle *trans,
 int btrfs_log_dentry_safe(struct btrfs_trans_handle *trans,
 			  struct btrfs_root *root, struct dentry *dentry)
 {
-	return btrfs_log_inode_parent(trans, root, dentry->d_inode,
-				      dentry->d_parent, 0);
+	struct dentry *parent = dget_parent(dentry);
+	int ret;
+
+	ret = btrfs_log_inode_parent(trans, root, dentry->d_inode, parent, 0);
+	dput(parent);
+
+	return ret;
 }
 
 /*