From 5d4f98a28c7d334091c1b7744f48a1acdd2a4ae0 Mon Sep 17 00:00:00 2001 From: Yan Zheng Date: Wed, 10 Jun 2009 10:45:14 -0400 Subject: Btrfs: Mixed back reference (FORWARD ROLLING FORMAT CHANGE) This commit introduces a new kind of back reference for btrfs metadata. Once a filesystem has been mounted with this commit, IT WILL NO LONGER BE MOUNTABLE BY OLDER KERNELS. When a tree block in subvolume tree is cow'd, the reference counts of all extents it points to are increased by one. At transaction commit time, the old root of the subvolume is recorded in a "dead root" data structure, and the btree it points to is later walked, dropping reference counts and freeing any blocks where the reference count goes to 0. The increments done during cow and decrements done after commit cancel out, and the walk is a very expensive way to go about freeing the blocks that are no longer referenced by the new btree root. This commit reduces the transaction overhead by avoiding the need for dead root records. When a non-shared tree block is cow'd, we free the old block at once, and the new block inherits old block's references. When a tree block with reference count > 1 is cow'd, we increase the reference counts of all extents the new block points to by one, and decrease the old block's reference count by one. This dead tree avoidance code removes the need to modify the reference counts of lower level extents when a non-shared tree block is cow'd. But we still need to update back ref for all pointers in the block. This is because the location of the block is recorded in the back ref item. We can solve this by introducing a new type of back ref. The new back ref provides information about pointer's key, level and in which tree the pointer lives. This information allow us to find the pointer by searching the tree. The shortcoming of the new back ref is that it only works for pointers in tree blocks referenced by their owner trees. This is mostly a problem for snapshots, where resolving one of these fuzzy back references would be O(number_of_snapshots) and quite slow. The solution used here is to use the fuzzy back references in the common case where a given tree block is only referenced by one root, and use the full back references when multiple roots have a reference on a given block. This commit adds per subvolume red-black tree to keep trace of cached inodes. The red-black tree helps the balancing code to find cached inodes whose inode numbers within a given range. This commit improves the balancing code by introducing several data structures to keep the state of balancing. The most important one is the back ref cache. It caches how the upper level tree blocks are referenced. This greatly reduce the overhead of checking back ref. The improved balancing code scales significantly better with a large number of snapshots. This is a very large commit and was written in a number of pieces. But, they depend heavily on the disk format change and were squashed together to make sure git bisect didn't end up in a bad state wrt space balancing or the format change. Signed-off-by: Yan Zheng Signed-off-by: Chris Mason --- fs/btrfs/disk-io.c | 95 ++++++++++++++++++++++++++++-------------------------- 1 file changed, 50 insertions(+), 45 deletions(-) (limited to 'fs/btrfs/disk-io.c') diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index 4b0ea0b80c2..7f5c6e3e999 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -36,7 +36,6 @@ #include "print-tree.h" #include "async-thread.h" #include "locking.h" -#include "ref-cache.h" #include "tree-log.h" #include "free-space-cache.h" @@ -884,7 +883,6 @@ static int __setup_root(u32 nodesize, u32 leafsize, u32 sectorsize, { root->node = NULL; root->commit_root = NULL; - root->ref_tree = NULL; root->sectorsize = sectorsize; root->nodesize = nodesize; root->leafsize = leafsize; @@ -899,12 +897,14 @@ static int __setup_root(u32 nodesize, u32 leafsize, u32 sectorsize, root->last_inode_alloc = 0; root->name = NULL; root->in_sysfs = 0; + root->inode_tree.rb_node = NULL; INIT_LIST_HEAD(&root->dirty_list); INIT_LIST_HEAD(&root->orphan_list); - INIT_LIST_HEAD(&root->dead_list); + INIT_LIST_HEAD(&root->root_list); spin_lock_init(&root->node_lock); spin_lock_init(&root->list_lock); + spin_lock_init(&root->inode_lock); mutex_init(&root->objectid_mutex); mutex_init(&root->log_mutex); init_waitqueue_head(&root->log_writer_wait); @@ -918,9 +918,6 @@ static int __setup_root(u32 nodesize, u32 leafsize, u32 sectorsize, extent_io_tree_init(&root->dirty_log_pages, fs_info->btree_inode->i_mapping, GFP_NOFS); - btrfs_leaf_ref_tree_init(&root->ref_tree_struct); - root->ref_tree = &root->ref_tree_struct; - memset(&root->root_key, 0, sizeof(root->root_key)); memset(&root->root_item, 0, sizeof(root->root_item)); memset(&root->defrag_progress, 0, sizeof(root->defrag_progress)); @@ -959,6 +956,7 @@ static int find_and_setup_root(struct btrfs_root *tree_root, blocksize = btrfs_level_size(root, btrfs_root_level(&root->root_item)); root->node = read_tree_block(root, btrfs_root_bytenr(&root->root_item), blocksize, generation); + root->commit_root = btrfs_root_node(root); BUG_ON(!root->node); return 0; } @@ -1025,20 +1023,19 @@ static struct btrfs_root *alloc_log_tree(struct btrfs_trans_handle *trans, */ root->ref_cows = 0; - leaf = btrfs_alloc_free_block(trans, root, root->leafsize, - 0, BTRFS_TREE_LOG_OBJECTID, - trans->transid, 0, 0, 0); + leaf = btrfs_alloc_free_block(trans, root, root->leafsize, 0, + BTRFS_TREE_LOG_OBJECTID, NULL, 0, 0, 0); if (IS_ERR(leaf)) { kfree(root); return ERR_CAST(leaf); } + memset_extent_buffer(leaf, 0, 0, sizeof(struct btrfs_header)); + btrfs_set_header_bytenr(leaf, leaf->start); + btrfs_set_header_generation(leaf, trans->transid); + btrfs_set_header_backref_rev(leaf, BTRFS_MIXED_BACKREF_REV); + btrfs_set_header_owner(leaf, BTRFS_TREE_LOG_OBJECTID); root->node = leaf; - btrfs_set_header_nritems(root->node, 0); - btrfs_set_header_level(root->node, 0); - btrfs_set_header_bytenr(root->node, root->node->start); - btrfs_set_header_generation(root->node, trans->transid); - btrfs_set_header_owner(root->node, BTRFS_TREE_LOG_OBJECTID); write_extent_buffer(root->node, root->fs_info->fsid, (unsigned long)btrfs_header_fsid(root->node), @@ -1081,8 +1078,7 @@ int btrfs_add_log_tree(struct btrfs_trans_handle *trans, inode_item->nbytes = cpu_to_le64(root->leafsize); inode_item->mode = cpu_to_le32(S_IFDIR | 0755); - btrfs_set_root_bytenr(&log_root->root_item, log_root->node->start); - btrfs_set_root_generation(&log_root->root_item, trans->transid); + btrfs_set_root_node(&log_root->root_item, log_root->node); WARN_ON(root->log_root); root->log_root = log_root; @@ -1144,6 +1140,7 @@ out: blocksize = btrfs_level_size(root, btrfs_root_level(&root->root_item)); root->node = read_tree_block(root, btrfs_root_bytenr(&root->root_item), blocksize, generation); + root->commit_root = btrfs_root_node(root); BUG_ON(!root->node); insert: if (location->objectid != BTRFS_TREE_LOG_OBJECTID) { @@ -1210,7 +1207,7 @@ struct btrfs_root *btrfs_read_fs_root_no_name(struct btrfs_fs_info *fs_info, } if (!(fs_info->sb->s_flags & MS_RDONLY)) { ret = btrfs_find_dead_roots(fs_info->tree_root, - root->root_key.objectid, root); + root->root_key.objectid); BUG_ON(ret); btrfs_orphan_cleanup(root); } @@ -1569,8 +1566,6 @@ struct btrfs_root *open_ctree(struct super_block *sb, atomic_set(&fs_info->async_delalloc_pages, 0); atomic_set(&fs_info->async_submit_draining, 0); atomic_set(&fs_info->nr_async_bios, 0); - atomic_set(&fs_info->throttles, 0); - atomic_set(&fs_info->throttle_gen, 0); fs_info->sb = sb; fs_info->max_extent = (u64)-1; fs_info->max_inline = 8192 * 1024; @@ -1598,6 +1593,7 @@ struct btrfs_root *open_ctree(struct super_block *sb, fs_info->btree_inode->i_mapping->a_ops = &btree_aops; fs_info->btree_inode->i_mapping->backing_dev_info = &fs_info->bdi; + RB_CLEAR_NODE(&BTRFS_I(fs_info->btree_inode)->rb_node); extent_io_tree_init(&BTRFS_I(fs_info->btree_inode)->io_tree, fs_info->btree_inode->i_mapping, GFP_NOFS); @@ -1613,10 +1609,6 @@ struct btrfs_root *open_ctree(struct super_block *sb, fs_info->btree_inode->i_mapping, GFP_NOFS); fs_info->do_barriers = 1; - INIT_LIST_HEAD(&fs_info->dead_reloc_roots); - btrfs_leaf_ref_tree_init(&fs_info->reloc_ref_tree); - btrfs_leaf_ref_tree_init(&fs_info->shared_ref_tree); - BTRFS_I(fs_info->btree_inode)->root = tree_root; memset(&BTRFS_I(fs_info->btree_inode)->location, 0, sizeof(struct btrfs_key)); @@ -1674,6 +1666,12 @@ struct btrfs_root *open_ctree(struct super_block *sb, goto fail_iput; } + features = btrfs_super_incompat_flags(disk_super); + if (!(features & BTRFS_FEATURE_INCOMPAT_MIXED_BACKREF)) { + features |= BTRFS_FEATURE_INCOMPAT_MIXED_BACKREF; + btrfs_set_super_incompat_flags(disk_super, features); + } + features = btrfs_super_compat_ro_flags(disk_super) & ~BTRFS_FEATURE_COMPAT_RO_SUPP; if (!(sb->s_flags & MS_RDONLY) && features) { @@ -1771,7 +1769,7 @@ struct btrfs_root *open_ctree(struct super_block *sb, if (ret) { printk(KERN_WARNING "btrfs: failed to read the system " "array on %s\n", sb->s_id); - goto fail_sys_array; + goto fail_sb_buffer; } blocksize = btrfs_level_size(tree_root, @@ -1785,6 +1783,8 @@ struct btrfs_root *open_ctree(struct super_block *sb, btrfs_super_chunk_root(disk_super), blocksize, generation); BUG_ON(!chunk_root->node); + btrfs_set_root_node(&chunk_root->root_item, chunk_root->node); + chunk_root->commit_root = btrfs_root_node(chunk_root); read_extent_buffer(chunk_root->node, fs_info->chunk_tree_uuid, (unsigned long)btrfs_header_chunk_tree_uuid(chunk_root->node), @@ -1810,7 +1810,8 @@ struct btrfs_root *open_ctree(struct super_block *sb, blocksize, generation); if (!tree_root->node) goto fail_chunk_root; - + btrfs_set_root_node(&tree_root->root_item, tree_root->node); + tree_root->commit_root = btrfs_root_node(tree_root); ret = find_and_setup_root(tree_root, fs_info, BTRFS_EXTENT_TREE_OBJECTID, extent_root); @@ -1820,14 +1821,14 @@ struct btrfs_root *open_ctree(struct super_block *sb, ret = find_and_setup_root(tree_root, fs_info, BTRFS_DEV_TREE_OBJECTID, dev_root); - dev_root->track_dirty = 1; if (ret) goto fail_extent_root; + dev_root->track_dirty = 1; ret = find_and_setup_root(tree_root, fs_info, BTRFS_CSUM_TREE_OBJECTID, csum_root); if (ret) - goto fail_extent_root; + goto fail_dev_root; csum_root->track_dirty = 1; @@ -1881,7 +1882,7 @@ struct btrfs_root *open_ctree(struct super_block *sb, } if (!(sb->s_flags & MS_RDONLY)) { - ret = btrfs_cleanup_reloc_trees(tree_root); + ret = btrfs_recover_relocation(tree_root); BUG_ON(ret); } @@ -1908,14 +1909,19 @@ fail_cleaner: fail_csum_root: free_extent_buffer(csum_root->node); + free_extent_buffer(csum_root->commit_root); +fail_dev_root: + free_extent_buffer(dev_root->node); + free_extent_buffer(dev_root->commit_root); fail_extent_root: free_extent_buffer(extent_root->node); + free_extent_buffer(extent_root->commit_root); fail_tree_root: free_extent_buffer(tree_root->node); + free_extent_buffer(tree_root->commit_root); fail_chunk_root: free_extent_buffer(chunk_root->node); -fail_sys_array: - free_extent_buffer(dev_root->node); + free_extent_buffer(chunk_root->commit_root); fail_sb_buffer: btrfs_stop_workers(&fs_info->fixup_workers); btrfs_stop_workers(&fs_info->delalloc_workers); @@ -2173,6 +2179,7 @@ int write_ctree_super(struct btrfs_trans_handle *trans, int btrfs_free_fs_root(struct btrfs_fs_info *fs_info, struct btrfs_root *root) { + WARN_ON(!RB_EMPTY_ROOT(&root->inode_tree)); radix_tree_delete(&fs_info->fs_roots_radix, (unsigned long)root->root_key.objectid); if (root->anon_super.s_dev) { @@ -2219,10 +2226,12 @@ int btrfs_cleanup_fs_roots(struct btrfs_fs_info *fs_info) ARRAY_SIZE(gang)); if (!ret) break; + + root_objectid = gang[ret - 1]->root_key.objectid + 1; for (i = 0; i < ret; i++) { root_objectid = gang[i]->root_key.objectid; ret = btrfs_find_dead_roots(fs_info->tree_root, - root_objectid, gang[i]); + root_objectid); BUG_ON(ret); btrfs_orphan_cleanup(gang[i]); } @@ -2278,20 +2287,16 @@ int close_ctree(struct btrfs_root *root) (unsigned long long)fs_info->total_ref_cache_size); } - if (fs_info->extent_root->node) - free_extent_buffer(fs_info->extent_root->node); - - if (fs_info->tree_root->node) - free_extent_buffer(fs_info->tree_root->node); - - if (root->fs_info->chunk_root->node) - free_extent_buffer(root->fs_info->chunk_root->node); - - if (root->fs_info->dev_root->node) - free_extent_buffer(root->fs_info->dev_root->node); - - if (root->fs_info->csum_root->node) - free_extent_buffer(root->fs_info->csum_root->node); + free_extent_buffer(fs_info->extent_root->node); + free_extent_buffer(fs_info->extent_root->commit_root); + free_extent_buffer(fs_info->tree_root->node); + free_extent_buffer(fs_info->tree_root->commit_root); + free_extent_buffer(root->fs_info->chunk_root->node); + free_extent_buffer(root->fs_info->chunk_root->commit_root); + free_extent_buffer(root->fs_info->dev_root->node); + free_extent_buffer(root->fs_info->dev_root->commit_root); + free_extent_buffer(root->fs_info->csum_root->node); + free_extent_buffer(root->fs_info->csum_root->commit_root); btrfs_free_block_groups(root->fs_info); -- cgit v1.2.3-18-g5258 From 585ad2c3797dcaa643aeba75b9f072778adf3490 Mon Sep 17 00:00:00 2001 From: Chris Mason Date: Mon, 18 May 2009 10:41:58 -0400 Subject: Btrfs: fix metadata dirty throttling limits Once a metadata block has been written, it must be recowed, so the btrfs dirty balancing call has a check to make sure a fair amount of metadata was actually dirty before it started writing it back to disk. A previous commit had changed the dirty tracking for metadata without updating the btrfs dirty balancing checks. This commit switches it to use the correct counter. Signed-off-by: Chris Mason --- fs/btrfs/disk-io.c | 7 ++----- 1 file changed, 2 insertions(+), 5 deletions(-) (limited to 'fs/btrfs/disk-io.c') diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index 7f5c6e3e999..e572cf478a5 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -2378,17 +2378,14 @@ void btrfs_btree_balance_dirty(struct btrfs_root *root, unsigned long nr) * looks as though older kernels can get into trouble with * this code, they end up stuck in balance_dirty_pages forever */ - struct extent_io_tree *tree; u64 num_dirty; - u64 start = 0; unsigned long thresh = 32 * 1024 * 1024; - tree = &BTRFS_I(root->fs_info->btree_inode)->io_tree; if (current->flags & PF_MEMALLOC) return; - num_dirty = count_range_bits(tree, &start, (u64)-1, - thresh, EXTENT_DIRTY); + num_dirty = root->fs_info->dirty_metadata_bytes; + if (num_dirty > thresh) { balance_dirty_pages_ratelimited_nr( root->fs_info->btree_inode->i_mapping, 1); -- cgit v1.2.3-18-g5258 From c289811cc096c57ff35550ee8132793a4f9b5b59 Mon Sep 17 00:00:00 2001 From: Chris Mason Date: Wed, 10 Jun 2009 09:51:32 -0400 Subject: Btrfs: autodetect SSD devices During mount, btrfs will check the queue nonrot flag for all the devices found in the FS. If they are all non-rotating, SSD mode is enabled by default. If the FS was mounted with -o nossd, the non-rotating flag is ignored. Signed-off-by: Chris Mason --- fs/btrfs/disk-io.c | 9 +++++++++ 1 file changed, 9 insertions(+) (limited to 'fs/btrfs/disk-io.c') diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index e572cf478a5..f4dfbb7ab49 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -1850,6 +1850,14 @@ struct btrfs_root *open_ctree(struct super_block *sb, if (IS_ERR(fs_info->transaction_kthread)) goto fail_cleaner; + if (!btrfs_test_opt(tree_root, SSD) && + !btrfs_test_opt(tree_root, NOSSD) && + !fs_info->fs_devices->rotating) { + printk(KERN_INFO "Btrfs detected SSD devices, enabling SSD " + "mode\n"); + btrfs_set_opt(fs_info->mount_opt, SSD); + } + if (btrfs_super_log_root(disk_super) != 0) { u64 bytenr = btrfs_super_log_root(disk_super); @@ -1893,6 +1901,7 @@ struct btrfs_root *open_ctree(struct super_block *sb, fs_info->fs_root = btrfs_read_fs_root_no_name(fs_info, &location); if (!fs_info->fs_root) goto fail_trans_kthread; + return tree_root; fail_trans_kthread: -- cgit v1.2.3-18-g5258 From 163e783e6a8b1e8bcb4c9084d438091386b589df Mon Sep 17 00:00:00 2001 From: David Woodhouse Date: Sun, 19 Apr 2009 13:02:41 +0100 Subject: Btrfs: remove crc32c.h and use libcrc32c directly. There's no need to preserve this abstraction; it used to let us use hardware crc32c support directly, but libcrc32c is already doing that for us through the crypto API -- so we're already using the Intel crc32c acceleration where appropriate. Signed-off-by: David Woodhouse Signed-off-by: Chris Mason --- fs/btrfs/disk-io.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'fs/btrfs/disk-io.c') diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index f4dfbb7ab49..6c54c210dfd 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -26,8 +26,8 @@ #include #include #include +#include #include "compat.h" -#include "crc32c.h" #include "ctree.h" #include "disk-io.h" #include "transaction.h" @@ -171,7 +171,7 @@ out: u32 btrfs_csum_data(struct btrfs_root *root, char *data, u32 seed, size_t len) { - return btrfs_crc32c(seed, data, len); + return crc32c(seed, data, len); } void btrfs_csum_final(u32 crc, char *result) -- cgit v1.2.3-18-g5258 From e5e9a5206a171b2c467e494aebcdcf70c47289bc Mon Sep 17 00:00:00 2001 From: Chris Mason Date: Wed, 10 Jun 2009 15:17:02 -0400 Subject: Btrfs: avoid races between super writeout and device list updates On multi-device filesystems, btrfs writes supers to all of the devices before considering a sync complete. There wasn't any additional locking between super writeout and the device list management code because device management was done inside a transaction and super writeout only happened with no transation writers running. With the btrfs fsync log and other async transaction updates, this has been racey for some time. This adds a mutex to protect the device list. The existing volume mutex could not be reused due to transaction lock ordering requirements. Signed-off-by: Chris Mason --- fs/btrfs/disk-io.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) (limited to 'fs/btrfs/disk-io.c') diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index 6c54c210dfd..b7ddc77fa56 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -2111,7 +2111,7 @@ static int write_dev_supers(struct btrfs_device *device, int write_all_supers(struct btrfs_root *root, int max_mirrors) { - struct list_head *head = &root->fs_info->fs_devices->devices; + struct list_head *head; struct btrfs_device *dev; struct btrfs_super_block *sb; struct btrfs_dev_item *dev_item; @@ -2126,6 +2126,9 @@ int write_all_supers(struct btrfs_root *root, int max_mirrors) sb = &root->fs_info->super_for_commit; dev_item = &sb->dev_item; + + mutex_lock(&root->fs_info->fs_devices->device_list_mutex); + head = &root->fs_info->fs_devices->devices; list_for_each_entry(dev, head, dev_list) { if (!dev->bdev) { total_errors++; @@ -2169,6 +2172,7 @@ int write_all_supers(struct btrfs_root *root, int max_mirrors) if (ret) total_errors++; } + mutex_unlock(&root->fs_info->fs_devices->device_list_mutex); if (total_errors > max_errors) { printk(KERN_ERR "btrfs: %d errors while writing supers\n", total_errors); -- cgit v1.2.3-18-g5258 From 4eedeb75e7f15ffdb12d1ad559b565e7505bdbaf Mon Sep 17 00:00:00 2001 From: Hisashi Hifumi Date: Wed, 10 Jun 2009 15:28:55 -0400 Subject: Btrfs: pin buffers during write_dev_supers write_dev_supers is called in sequence. First is it called with wait == 0, which starts IO on all of the super blocks for a given device. Then it is called with wait == 1 to make sure they all reach the disk. It doesn't currently pin the buffers between the two calls, and it also assumes the buffers won't go away between the two calls, leading to an oops if the VM manages to free the buffers in the middle of the sync. This fixes that assumption and updates the code to return an error if things are not up to date when the wait == 1 run is done. Signed-off-by: Hisashi Hifumi Signed-off-by: Chris Mason --- fs/btrfs/disk-io.c | 43 +++++++++++++++++++++++++++++-------------- 1 file changed, 29 insertions(+), 14 deletions(-) (limited to 'fs/btrfs/disk-io.c') diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index b7ddc77fa56..0d50d49d990 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -2020,6 +2020,17 @@ struct buffer_head *btrfs_read_dev_super(struct block_device *bdev) return latest; } +/* + * this should be called twice, once with wait == 0 and + * once with wait == 1. When wait == 0 is done, all the buffer heads + * we write are pinned. + * + * They are released when wait == 1 is done. + * max_mirrors must be the same for both runs, and it indicates how + * many supers on this one device should be written. + * + * max_mirrors == 0 means to write them all. + */ static int write_dev_supers(struct btrfs_device *device, struct btrfs_super_block *sb, int do_barriers, int wait, int max_mirrors) @@ -2055,12 +2066,16 @@ static int write_dev_supers(struct btrfs_device *device, bh = __find_get_block(device->bdev, bytenr / 4096, BTRFS_SUPER_INFO_SIZE); BUG_ON(!bh); - brelse(bh); wait_on_buffer(bh); - if (buffer_uptodate(bh)) { - brelse(bh); - continue; - } + if (!buffer_uptodate(bh)) + errors++; + + /* drop our reference */ + brelse(bh); + + /* drop the reference from the wait == 0 run */ + brelse(bh); + continue; } else { btrfs_set_super_bytenr(sb, bytenr); @@ -2071,12 +2086,18 @@ static int write_dev_supers(struct btrfs_device *device, BTRFS_CSUM_SIZE); btrfs_csum_final(crc, sb->csum); + /* + * one reference for us, and we leave it for the + * caller + */ bh = __getblk(device->bdev, bytenr / 4096, BTRFS_SUPER_INFO_SIZE); memcpy(bh->b_data, sb, BTRFS_SUPER_INFO_SIZE); - set_buffer_uptodate(bh); + /* one reference for submit_bh */ get_bh(bh); + + set_buffer_uptodate(bh); lock_buffer(bh); bh->b_end_io = btrfs_end_buffer_write_sync; } @@ -2088,6 +2109,7 @@ static int write_dev_supers(struct btrfs_device *device, device->name); set_buffer_uptodate(bh); device->barriers = 0; + /* one reference for submit_bh */ get_bh(bh); lock_buffer(bh); ret = submit_bh(WRITE_SYNC, bh); @@ -2096,15 +2118,8 @@ static int write_dev_supers(struct btrfs_device *device, ret = submit_bh(WRITE_SYNC, bh); } - if (!ret && wait) { - wait_on_buffer(bh); - if (!buffer_uptodate(bh)) - errors++; - } else if (ret) { + if (ret) errors++; - } - if (wait) - brelse(bh); } return errors < i ? 0 : -1; } -- cgit v1.2.3-18-g5258