This can be easily migrated over now.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ update comments ]
Signed-off-by: David Sterba <dsterba@suse.com>
#include "ref-verify.h"
#include "sysfs.h"
#include "tree-log.h"
+#include "delalloc-space.h"
void btrfs_get_block_group(struct btrfs_block_group_cache *cache)
{
spin_unlock(&cache->lock);
spin_unlock(&sinfo->lock);
}
+
+static int write_one_cache_group(struct btrfs_trans_handle *trans,
+ struct btrfs_path *path,
+ struct btrfs_block_group_cache *cache)
+{
+ struct btrfs_fs_info *fs_info = trans->fs_info;
+ int ret;
+ struct btrfs_root *extent_root = fs_info->extent_root;
+ unsigned long bi;
+ struct extent_buffer *leaf;
+
+ ret = btrfs_search_slot(trans, extent_root, &cache->key, path, 0, 1);
+ if (ret) {
+ if (ret > 0)
+ ret = -ENOENT;
+ goto fail;
+ }
+
+ leaf = path->nodes[0];
+ bi = btrfs_item_ptr_offset(leaf, path->slots[0]);
+ write_extent_buffer(leaf, &cache->item, bi, sizeof(cache->item));
+ btrfs_mark_buffer_dirty(leaf);
+fail:
+ btrfs_release_path(path);
+ return ret;
+
+}
+
+static int cache_save_setup(struct btrfs_block_group_cache *block_group,
+ struct btrfs_trans_handle *trans,
+ struct btrfs_path *path)
+{
+ struct btrfs_fs_info *fs_info = block_group->fs_info;
+ struct btrfs_root *root = fs_info->tree_root;
+ struct inode *inode = NULL;
+ struct extent_changeset *data_reserved = NULL;
+ u64 alloc_hint = 0;
+ int dcs = BTRFS_DC_ERROR;
+ u64 num_pages = 0;
+ int retries = 0;
+ int ret = 0;
+
+ /*
+ * If this block group is smaller than 100 megs don't bother caching the
+ * block group.
+ */
+ if (block_group->key.offset < (100 * SZ_1M)) {
+ spin_lock(&block_group->lock);
+ block_group->disk_cache_state = BTRFS_DC_WRITTEN;
+ spin_unlock(&block_group->lock);
+ return 0;
+ }
+
+ if (trans->aborted)
+ return 0;
+again:
+ inode = lookup_free_space_inode(block_group, path);
+ if (IS_ERR(inode) && PTR_ERR(inode) != -ENOENT) {
+ ret = PTR_ERR(inode);
+ btrfs_release_path(path);
+ goto out;
+ }
+
+ if (IS_ERR(inode)) {
+ BUG_ON(retries);
+ retries++;
+
+ if (block_group->ro)
+ goto out_free;
+
+ ret = create_free_space_inode(trans, block_group, path);
+ if (ret)
+ goto out_free;
+ goto again;
+ }
+
+ /*
+ * We want to set the generation to 0, that way if anything goes wrong
+ * from here on out we know not to trust this cache when we load up next
+ * time.
+ */
+ BTRFS_I(inode)->generation = 0;
+ ret = btrfs_update_inode(trans, root, inode);
+ if (ret) {
+ /*
+ * So theoretically we could recover from this, simply set the
+ * super cache generation to 0 so we know to invalidate the
+ * cache, but then we'd have to keep track of the block groups
+ * that fail this way so we know we _have_ to reset this cache
+ * before the next commit or risk reading stale cache. So to
+ * limit our exposure to horrible edge cases lets just abort the
+ * transaction, this only happens in really bad situations
+ * anyway.
+ */
+ btrfs_abort_transaction(trans, ret);
+ goto out_put;
+ }
+ WARN_ON(ret);
+
+ /* We've already setup this transaction, go ahead and exit */
+ if (block_group->cache_generation == trans->transid &&
+ i_size_read(inode)) {
+ dcs = BTRFS_DC_SETUP;
+ goto out_put;
+ }
+
+ if (i_size_read(inode) > 0) {
+ ret = btrfs_check_trunc_cache_free_space(fs_info,
+ &fs_info->global_block_rsv);
+ if (ret)
+ goto out_put;
+
+ ret = btrfs_truncate_free_space_cache(trans, NULL, inode);
+ if (ret)
+ goto out_put;
+ }
+
+ spin_lock(&block_group->lock);
+ if (block_group->cached != BTRFS_CACHE_FINISHED ||
+ !btrfs_test_opt(fs_info, SPACE_CACHE)) {
+ /*
+ * don't bother trying to write stuff out _if_
+ * a) we're not cached,
+ * b) we're with nospace_cache mount option,
+ * c) we're with v2 space_cache (FREE_SPACE_TREE).
+ */
+ dcs = BTRFS_DC_WRITTEN;
+ spin_unlock(&block_group->lock);
+ goto out_put;
+ }
+ spin_unlock(&block_group->lock);
+
+ /*
+ * We hit an ENOSPC when setting up the cache in this transaction, just
+ * skip doing the setup, we've already cleared the cache so we're safe.
+ */
+ if (test_bit(BTRFS_TRANS_CACHE_ENOSPC, &trans->transaction->flags)) {
+ ret = -ENOSPC;
+ goto out_put;
+ }
+
+ /*
+ * Try to preallocate enough space based on how big the block group is.
+ * Keep in mind this has to include any pinned space which could end up
+ * taking up quite a bit since it's not folded into the other space
+ * cache.
+ */
+ num_pages = div_u64(block_group->key.offset, SZ_256M);
+ if (!num_pages)
+ num_pages = 1;
+
+ num_pages *= 16;
+ num_pages *= PAGE_SIZE;
+
+ ret = btrfs_check_data_free_space(inode, &data_reserved, 0, num_pages);
+ if (ret)
+ goto out_put;
+
+ ret = btrfs_prealloc_file_range_trans(inode, trans, 0, 0, num_pages,
+ num_pages, num_pages,
+ &alloc_hint);
+ /*
+ * Our cache requires contiguous chunks so that we don't modify a bunch
+ * of metadata or split extents when writing the cache out, which means
+ * we can enospc if we are heavily fragmented in addition to just normal
+ * out of space conditions. So if we hit this just skip setting up any
+ * other block groups for this transaction, maybe we'll unpin enough
+ * space the next time around.
+ */
+ if (!ret)
+ dcs = BTRFS_DC_SETUP;
+ else if (ret == -ENOSPC)
+ set_bit(BTRFS_TRANS_CACHE_ENOSPC, &trans->transaction->flags);
+
+out_put:
+ iput(inode);
+out_free:
+ btrfs_release_path(path);
+out:
+ spin_lock(&block_group->lock);
+ if (!ret && dcs == BTRFS_DC_SETUP)
+ block_group->cache_generation = trans->transid;
+ block_group->disk_cache_state = dcs;
+ spin_unlock(&block_group->lock);
+
+ extent_changeset_free(data_reserved);
+ return ret;
+}
+
+int btrfs_setup_space_cache(struct btrfs_trans_handle *trans)
+{
+ struct btrfs_fs_info *fs_info = trans->fs_info;
+ struct btrfs_block_group_cache *cache, *tmp;
+ struct btrfs_transaction *cur_trans = trans->transaction;
+ struct btrfs_path *path;
+
+ if (list_empty(&cur_trans->dirty_bgs) ||
+ !btrfs_test_opt(fs_info, SPACE_CACHE))
+ return 0;
+
+ path = btrfs_alloc_path();
+ if (!path)
+ return -ENOMEM;
+
+ /* Could add new block groups, use _safe just in case */
+ list_for_each_entry_safe(cache, tmp, &cur_trans->dirty_bgs,
+ dirty_list) {
+ if (cache->disk_cache_state == BTRFS_DC_CLEAR)
+ cache_save_setup(cache, trans, path);
+ }
+
+ btrfs_free_path(path);
+ return 0;
+}
+
+/*
+ * Transaction commit does final block group cache writeback during a critical
+ * section where nothing is allowed to change the FS. This is required in
+ * order for the cache to actually match the block group, but can introduce a
+ * lot of latency into the commit.
+ *
+ * So, btrfs_start_dirty_block_groups is here to kick off block group cache IO.
+ * There's a chance we'll have to redo some of it if the block group changes
+ * again during the commit, but it greatly reduces the commit latency by
+ * getting rid of the easy block groups while we're still allowing others to
+ * join the commit.
+ */
+int btrfs_start_dirty_block_groups(struct btrfs_trans_handle *trans)
+{
+ struct btrfs_fs_info *fs_info = trans->fs_info;
+ struct btrfs_block_group_cache *cache;
+ struct btrfs_transaction *cur_trans = trans->transaction;
+ int ret = 0;
+ int should_put;
+ struct btrfs_path *path = NULL;
+ LIST_HEAD(dirty);
+ struct list_head *io = &cur_trans->io_bgs;
+ int num_started = 0;
+ int loops = 0;
+
+ spin_lock(&cur_trans->dirty_bgs_lock);
+ if (list_empty(&cur_trans->dirty_bgs)) {
+ spin_unlock(&cur_trans->dirty_bgs_lock);
+ return 0;
+ }
+ list_splice_init(&cur_trans->dirty_bgs, &dirty);
+ spin_unlock(&cur_trans->dirty_bgs_lock);
+
+again:
+ /* Make sure all the block groups on our dirty list actually exist */
+ btrfs_create_pending_block_groups(trans);
+
+ if (!path) {
+ path = btrfs_alloc_path();
+ if (!path)
+ return -ENOMEM;
+ }
+
+ /*
+ * cache_write_mutex is here only to save us from balance or automatic
+ * removal of empty block groups deleting this block group while we are
+ * writing out the cache
+ */
+ mutex_lock(&trans->transaction->cache_write_mutex);
+ while (!list_empty(&dirty)) {
+ bool drop_reserve = true;
+
+ cache = list_first_entry(&dirty,
+ struct btrfs_block_group_cache,
+ dirty_list);
+ /*
+ * This can happen if something re-dirties a block group that
+ * is already under IO. Just wait for it to finish and then do
+ * it all again
+ */
+ if (!list_empty(&cache->io_list)) {
+ list_del_init(&cache->io_list);
+ btrfs_wait_cache_io(trans, cache, path);
+ btrfs_put_block_group(cache);
+ }
+
+
+ /*
+ * btrfs_wait_cache_io uses the cache->dirty_list to decide if
+ * it should update the cache_state. Don't delete until after
+ * we wait.
+ *
+ * Since we're not running in the commit critical section
+ * we need the dirty_bgs_lock to protect from update_block_group
+ */
+ spin_lock(&cur_trans->dirty_bgs_lock);
+ list_del_init(&cache->dirty_list);
+ spin_unlock(&cur_trans->dirty_bgs_lock);
+
+ should_put = 1;
+
+ cache_save_setup(cache, trans, path);
+
+ if (cache->disk_cache_state == BTRFS_DC_SETUP) {
+ cache->io_ctl.inode = NULL;
+ ret = btrfs_write_out_cache(trans, cache, path);
+ if (ret == 0 && cache->io_ctl.inode) {
+ num_started++;
+ should_put = 0;
+
+ /*
+ * The cache_write_mutex is protecting the
+ * io_list, also refer to the definition of
+ * btrfs_transaction::io_bgs for more details
+ */
+ list_add_tail(&cache->io_list, io);
+ } else {
+ /*
+ * If we failed to write the cache, the
+ * generation will be bad and life goes on
+ */
+ ret = 0;
+ }
+ }
+ if (!ret) {
+ ret = write_one_cache_group(trans, path, cache);
+ /*
+ * Our block group might still be attached to the list
+ * of new block groups in the transaction handle of some
+ * other task (struct btrfs_trans_handle->new_bgs). This
+ * means its block group item isn't yet in the extent
+ * tree. If this happens ignore the error, as we will
+ * try again later in the critical section of the
+ * transaction commit.
+ */
+ if (ret == -ENOENT) {
+ ret = 0;
+ spin_lock(&cur_trans->dirty_bgs_lock);
+ if (list_empty(&cache->dirty_list)) {
+ list_add_tail(&cache->dirty_list,
+ &cur_trans->dirty_bgs);
+ btrfs_get_block_group(cache);
+ drop_reserve = false;
+ }
+ spin_unlock(&cur_trans->dirty_bgs_lock);
+ } else if (ret) {
+ btrfs_abort_transaction(trans, ret);
+ }
+ }
+
+ /* If it's not on the io list, we need to put the block group */
+ if (should_put)
+ btrfs_put_block_group(cache);
+ if (drop_reserve)
+ btrfs_delayed_refs_rsv_release(fs_info, 1);
+
+ if (ret)
+ break;
+
+ /*
+ * Avoid blocking other tasks for too long. It might even save
+ * us from writing caches for block groups that are going to be
+ * removed.
+ */
+ mutex_unlock(&trans->transaction->cache_write_mutex);
+ mutex_lock(&trans->transaction->cache_write_mutex);
+ }
+ mutex_unlock(&trans->transaction->cache_write_mutex);
+
+ /*
+ * Go through delayed refs for all the stuff we've just kicked off
+ * and then loop back (just once)
+ */
+ ret = btrfs_run_delayed_refs(trans, 0);
+ if (!ret && loops == 0) {
+ loops++;
+ spin_lock(&cur_trans->dirty_bgs_lock);
+ list_splice_init(&cur_trans->dirty_bgs, &dirty);
+ /*
+ * dirty_bgs_lock protects us from concurrent block group
+ * deletes too (not just cache_write_mutex).
+ */
+ if (!list_empty(&dirty)) {
+ spin_unlock(&cur_trans->dirty_bgs_lock);
+ goto again;
+ }
+ spin_unlock(&cur_trans->dirty_bgs_lock);
+ } else if (ret < 0) {
+ btrfs_cleanup_dirty_bgs(cur_trans, fs_info);
+ }
+
+ btrfs_free_path(path);
+ return ret;
+}
+
+int btrfs_write_dirty_block_groups(struct btrfs_trans_handle *trans)
+{
+ struct btrfs_fs_info *fs_info = trans->fs_info;
+ struct btrfs_block_group_cache *cache;
+ struct btrfs_transaction *cur_trans = trans->transaction;
+ int ret = 0;
+ int should_put;
+ struct btrfs_path *path;
+ struct list_head *io = &cur_trans->io_bgs;
+ int num_started = 0;
+
+ path = btrfs_alloc_path();
+ if (!path)
+ return -ENOMEM;
+
+ /*
+ * Even though we are in the critical section of the transaction commit,
+ * we can still have concurrent tasks adding elements to this
+ * transaction's list of dirty block groups. These tasks correspond to
+ * endio free space workers started when writeback finishes for a
+ * space cache, which run inode.c:btrfs_finish_ordered_io(), and can
+ * allocate new block groups as a result of COWing nodes of the root
+ * tree when updating the free space inode. The writeback for the space
+ * caches is triggered by an earlier call to
+ * btrfs_start_dirty_block_groups() and iterations of the following
+ * loop.
+ * Also we want to do the cache_save_setup first and then run the
+ * delayed refs to make sure we have the best chance at doing this all
+ * in one shot.
+ */
+ spin_lock(&cur_trans->dirty_bgs_lock);
+ while (!list_empty(&cur_trans->dirty_bgs)) {
+ cache = list_first_entry(&cur_trans->dirty_bgs,
+ struct btrfs_block_group_cache,
+ dirty_list);
+
+ /*
+ * This can happen if cache_save_setup re-dirties a block group
+ * that is already under IO. Just wait for it to finish and
+ * then do it all again
+ */
+ if (!list_empty(&cache->io_list)) {
+ spin_unlock(&cur_trans->dirty_bgs_lock);
+ list_del_init(&cache->io_list);
+ btrfs_wait_cache_io(trans, cache, path);
+ btrfs_put_block_group(cache);
+ spin_lock(&cur_trans->dirty_bgs_lock);
+ }
+
+ /*
+ * Don't remove from the dirty list until after we've waited on
+ * any pending IO
+ */
+ list_del_init(&cache->dirty_list);
+ spin_unlock(&cur_trans->dirty_bgs_lock);
+ should_put = 1;
+
+ cache_save_setup(cache, trans, path);
+
+ if (!ret)
+ ret = btrfs_run_delayed_refs(trans,
+ (unsigned long) -1);
+
+ if (!ret && cache->disk_cache_state == BTRFS_DC_SETUP) {
+ cache->io_ctl.inode = NULL;
+ ret = btrfs_write_out_cache(trans, cache, path);
+ if (ret == 0 && cache->io_ctl.inode) {
+ num_started++;
+ should_put = 0;
+ list_add_tail(&cache->io_list, io);
+ } else {
+ /*
+ * If we failed to write the cache, the
+ * generation will be bad and life goes on
+ */
+ ret = 0;
+ }
+ }
+ if (!ret) {
+ ret = write_one_cache_group(trans, path, cache);
+ /*
+ * One of the free space endio workers might have
+ * created a new block group while updating a free space
+ * cache's inode (at inode.c:btrfs_finish_ordered_io())
+ * and hasn't released its transaction handle yet, in
+ * which case the new block group is still attached to
+ * its transaction handle and its creation has not
+ * finished yet (no block group item in the extent tree
+ * yet, etc). If this is the case, wait for all free
+ * space endio workers to finish and retry. This is a
+ * a very rare case so no need for a more efficient and
+ * complex approach.
+ */
+ if (ret == -ENOENT) {
+ wait_event(cur_trans->writer_wait,
+ atomic_read(&cur_trans->num_writers) == 1);
+ ret = write_one_cache_group(trans, path, cache);
+ }
+ if (ret)
+ btrfs_abort_transaction(trans, ret);
+ }
+
+ /* If its not on the io list, we need to put the block group */
+ if (should_put)
+ btrfs_put_block_group(cache);
+ btrfs_delayed_refs_rsv_release(fs_info, 1);
+ spin_lock(&cur_trans->dirty_bgs_lock);
+ }
+ spin_unlock(&cur_trans->dirty_bgs_lock);
+
+ /*
+ * Refer to the definition of io_bgs member for details why it's safe
+ * to use it without any locking
+ */
+ while (!list_empty(io)) {
+ cache = list_first_entry(io, struct btrfs_block_group_cache,
+ io_list);
+ list_del_init(&cache->io_list);
+ btrfs_wait_cache_io(trans, cache, path);
+ btrfs_put_block_group(cache);
+ }
+
+ btrfs_free_path(path);
+ return ret;
+}
void btrfs_create_pending_block_groups(struct btrfs_trans_handle *trans);
int btrfs_inc_block_group_ro(struct btrfs_block_group_cache *cache);
void btrfs_dec_block_group_ro(struct btrfs_block_group_cache *cache);
+int btrfs_start_dirty_block_groups(struct btrfs_trans_handle *trans);
+int btrfs_write_dirty_block_groups(struct btrfs_trans_handle *trans);
+int btrfs_setup_space_cache(struct btrfs_trans_handle *trans);
static inline int btrfs_block_group_cache_done(
struct btrfs_block_group_cache *cache)
int btrfs_inc_extent_ref(struct btrfs_trans_handle *trans,
struct btrfs_ref *generic_ref);
-int btrfs_start_dirty_block_groups(struct btrfs_trans_handle *trans);
-int btrfs_write_dirty_block_groups(struct btrfs_trans_handle *trans);
-int btrfs_setup_space_cache(struct btrfs_trans_handle *trans);
int btrfs_extent_readonly(struct btrfs_fs_info *fs_info, u64 bytenr);
int btrfs_free_block_groups(struct btrfs_fs_info *info);
void btrfs_get_block_group_trimming(struct btrfs_block_group_cache *cache);
return __btrfs_mod_ref(trans, root, buf, full_backref, 0);
}
-static int write_one_cache_group(struct btrfs_trans_handle *trans,
- struct btrfs_path *path,
- struct btrfs_block_group_cache *cache)
-{
- struct btrfs_fs_info *fs_info = trans->fs_info;
- int ret;
- struct btrfs_root *extent_root = fs_info->extent_root;
- unsigned long bi;
- struct extent_buffer *leaf;
-
- ret = btrfs_search_slot(trans, extent_root, &cache->key, path, 0, 1);
- if (ret) {
- if (ret > 0)
- ret = -ENOENT;
- goto fail;
- }
-
- leaf = path->nodes[0];
- bi = btrfs_item_ptr_offset(leaf, path->slots[0]);
- write_extent_buffer(leaf, &cache->item, bi, sizeof(cache->item));
- btrfs_mark_buffer_dirty(leaf);
-fail:
- btrfs_release_path(path);
- return ret;
-
-}
-
-static int cache_save_setup(struct btrfs_block_group_cache *block_group,
- struct btrfs_trans_handle *trans,
- struct btrfs_path *path)
-{
- struct btrfs_fs_info *fs_info = block_group->fs_info;
- struct btrfs_root *root = fs_info->tree_root;
- struct inode *inode = NULL;
- struct extent_changeset *data_reserved = NULL;
- u64 alloc_hint = 0;
- int dcs = BTRFS_DC_ERROR;
- u64 num_pages = 0;
- int retries = 0;
- int ret = 0;
-
- /*
- * If this block group is smaller than 100 megs don't bother caching the
- * block group.
- */
- if (block_group->key.offset < (100 * SZ_1M)) {
- spin_lock(&block_group->lock);
- block_group->disk_cache_state = BTRFS_DC_WRITTEN;
- spin_unlock(&block_group->lock);
- return 0;
- }
-
- if (trans->aborted)
- return 0;
-again:
- inode = lookup_free_space_inode(block_group, path);
- if (IS_ERR(inode) && PTR_ERR(inode) != -ENOENT) {
- ret = PTR_ERR(inode);
- btrfs_release_path(path);
- goto out;
- }
-
- if (IS_ERR(inode)) {
- BUG_ON(retries);
- retries++;
-
- if (block_group->ro)
- goto out_free;
-
- ret = create_free_space_inode(trans, block_group, path);
- if (ret)
- goto out_free;
- goto again;
- }
-
- /*
- * We want to set the generation to 0, that way if anything goes wrong
- * from here on out we know not to trust this cache when we load up next
- * time.
- */
- BTRFS_I(inode)->generation = 0;
- ret = btrfs_update_inode(trans, root, inode);
- if (ret) {
- /*
- * So theoretically we could recover from this, simply set the
- * super cache generation to 0 so we know to invalidate the
- * cache, but then we'd have to keep track of the block groups
- * that fail this way so we know we _have_ to reset this cache
- * before the next commit or risk reading stale cache. So to
- * limit our exposure to horrible edge cases lets just abort the
- * transaction, this only happens in really bad situations
- * anyway.
- */
- btrfs_abort_transaction(trans, ret);
- goto out_put;
- }
- WARN_ON(ret);
-
- /* We've already setup this transaction, go ahead and exit */
- if (block_group->cache_generation == trans->transid &&
- i_size_read(inode)) {
- dcs = BTRFS_DC_SETUP;
- goto out_put;
- }
-
- if (i_size_read(inode) > 0) {
- ret = btrfs_check_trunc_cache_free_space(fs_info,
- &fs_info->global_block_rsv);
- if (ret)
- goto out_put;
-
- ret = btrfs_truncate_free_space_cache(trans, NULL, inode);
- if (ret)
- goto out_put;
- }
-
- spin_lock(&block_group->lock);
- if (block_group->cached != BTRFS_CACHE_FINISHED ||
- !btrfs_test_opt(fs_info, SPACE_CACHE)) {
- /*
- * don't bother trying to write stuff out _if_
- * a) we're not cached,
- * b) we're with nospace_cache mount option,
- * c) we're with v2 space_cache (FREE_SPACE_TREE).
- */
- dcs = BTRFS_DC_WRITTEN;
- spin_unlock(&block_group->lock);
- goto out_put;
- }
- spin_unlock(&block_group->lock);
-
- /*
- * We hit an ENOSPC when setting up the cache in this transaction, just
- * skip doing the setup, we've already cleared the cache so we're safe.
- */
- if (test_bit(BTRFS_TRANS_CACHE_ENOSPC, &trans->transaction->flags)) {
- ret = -ENOSPC;
- goto out_put;
- }
-
- /*
- * Try to preallocate enough space based on how big the block group is.
- * Keep in mind this has to include any pinned space which could end up
- * taking up quite a bit since it's not folded into the other space
- * cache.
- */
- num_pages = div_u64(block_group->key.offset, SZ_256M);
- if (!num_pages)
- num_pages = 1;
-
- num_pages *= 16;
- num_pages *= PAGE_SIZE;
-
- ret = btrfs_check_data_free_space(inode, &data_reserved, 0, num_pages);
- if (ret)
- goto out_put;
-
- ret = btrfs_prealloc_file_range_trans(inode, trans, 0, 0, num_pages,
- num_pages, num_pages,
- &alloc_hint);
- /*
- * Our cache requires contiguous chunks so that we don't modify a bunch
- * of metadata or split extents when writing the cache out, which means
- * we can enospc if we are heavily fragmented in addition to just normal
- * out of space conditions. So if we hit this just skip setting up any
- * other block groups for this transaction, maybe we'll unpin enough
- * space the next time around.
- */
- if (!ret)
- dcs = BTRFS_DC_SETUP;
- else if (ret == -ENOSPC)
- set_bit(BTRFS_TRANS_CACHE_ENOSPC, &trans->transaction->flags);
-
-out_put:
- iput(inode);
-out_free:
- btrfs_release_path(path);
-out:
- spin_lock(&block_group->lock);
- if (!ret && dcs == BTRFS_DC_SETUP)
- block_group->cache_generation = trans->transid;
- block_group->disk_cache_state = dcs;
- spin_unlock(&block_group->lock);
-
- extent_changeset_free(data_reserved);
- return ret;
-}
-
-int btrfs_setup_space_cache(struct btrfs_trans_handle *trans)
-{
- struct btrfs_fs_info *fs_info = trans->fs_info;
- struct btrfs_block_group_cache *cache, *tmp;
- struct btrfs_transaction *cur_trans = trans->transaction;
- struct btrfs_path *path;
-
- if (list_empty(&cur_trans->dirty_bgs) ||
- !btrfs_test_opt(fs_info, SPACE_CACHE))
- return 0;
-
- path = btrfs_alloc_path();
- if (!path)
- return -ENOMEM;
-
- /* Could add new block groups, use _safe just in case */
- list_for_each_entry_safe(cache, tmp, &cur_trans->dirty_bgs,
- dirty_list) {
- if (cache->disk_cache_state == BTRFS_DC_CLEAR)
- cache_save_setup(cache, trans, path);
- }
-
- btrfs_free_path(path);
- return 0;
-}
-
-/*
- * transaction commit does final block group cache writeback during a
- * critical section where nothing is allowed to change the FS. This is
- * required in order for the cache to actually match the block group,
- * but can introduce a lot of latency into the commit.
- *
- * So, btrfs_start_dirty_block_groups is here to kick off block group
- * cache IO. There's a chance we'll have to redo some of it if the
- * block group changes again during the commit, but it greatly reduces
- * the commit latency by getting rid of the easy block groups while
- * we're still allowing others to join the commit.
- */
-int btrfs_start_dirty_block_groups(struct btrfs_trans_handle *trans)
-{
- struct btrfs_fs_info *fs_info = trans->fs_info;
- struct btrfs_block_group_cache *cache;
- struct btrfs_transaction *cur_trans = trans->transaction;
- int ret = 0;
- int should_put;
- struct btrfs_path *path = NULL;
- LIST_HEAD(dirty);
- struct list_head *io = &cur_trans->io_bgs;
- int num_started = 0;
- int loops = 0;
-
- spin_lock(&cur_trans->dirty_bgs_lock);
- if (list_empty(&cur_trans->dirty_bgs)) {
- spin_unlock(&cur_trans->dirty_bgs_lock);
- return 0;
- }
- list_splice_init(&cur_trans->dirty_bgs, &dirty);
- spin_unlock(&cur_trans->dirty_bgs_lock);
-
-again:
- /*
- * make sure all the block groups on our dirty list actually
- * exist
- */
- btrfs_create_pending_block_groups(trans);
-
- if (!path) {
- path = btrfs_alloc_path();
- if (!path)
- return -ENOMEM;
- }
-
- /*
- * cache_write_mutex is here only to save us from balance or automatic
- * removal of empty block groups deleting this block group while we are
- * writing out the cache
- */
- mutex_lock(&trans->transaction->cache_write_mutex);
- while (!list_empty(&dirty)) {
- bool drop_reserve = true;
-
- cache = list_first_entry(&dirty,
- struct btrfs_block_group_cache,
- dirty_list);
- /*
- * this can happen if something re-dirties a block
- * group that is already under IO. Just wait for it to
- * finish and then do it all again
- */
- if (!list_empty(&cache->io_list)) {
- list_del_init(&cache->io_list);
- btrfs_wait_cache_io(trans, cache, path);
- btrfs_put_block_group(cache);
- }
-
-
- /*
- * btrfs_wait_cache_io uses the cache->dirty_list to decide
- * if it should update the cache_state. Don't delete
- * until after we wait.
- *
- * Since we're not running in the commit critical section
- * we need the dirty_bgs_lock to protect from update_block_group
- */
- spin_lock(&cur_trans->dirty_bgs_lock);
- list_del_init(&cache->dirty_list);
- spin_unlock(&cur_trans->dirty_bgs_lock);
-
- should_put = 1;
-
- cache_save_setup(cache, trans, path);
-
- if (cache->disk_cache_state == BTRFS_DC_SETUP) {
- cache->io_ctl.inode = NULL;
- ret = btrfs_write_out_cache(trans, cache, path);
- if (ret == 0 && cache->io_ctl.inode) {
- num_started++;
- should_put = 0;
-
- /*
- * The cache_write_mutex is protecting the
- * io_list, also refer to the definition of
- * btrfs_transaction::io_bgs for more details
- */
- list_add_tail(&cache->io_list, io);
- } else {
- /*
- * if we failed to write the cache, the
- * generation will be bad and life goes on
- */
- ret = 0;
- }
- }
- if (!ret) {
- ret = write_one_cache_group(trans, path, cache);
- /*
- * Our block group might still be attached to the list
- * of new block groups in the transaction handle of some
- * other task (struct btrfs_trans_handle->new_bgs). This
- * means its block group item isn't yet in the extent
- * tree. If this happens ignore the error, as we will
- * try again later in the critical section of the
- * transaction commit.
- */
- if (ret == -ENOENT) {
- ret = 0;
- spin_lock(&cur_trans->dirty_bgs_lock);
- if (list_empty(&cache->dirty_list)) {
- list_add_tail(&cache->dirty_list,
- &cur_trans->dirty_bgs);
- btrfs_get_block_group(cache);
- drop_reserve = false;
- }
- spin_unlock(&cur_trans->dirty_bgs_lock);
- } else if (ret) {
- btrfs_abort_transaction(trans, ret);
- }
- }
-
- /* if it's not on the io list, we need to put the block group */
- if (should_put)
- btrfs_put_block_group(cache);
- if (drop_reserve)
- btrfs_delayed_refs_rsv_release(fs_info, 1);
-
- if (ret)
- break;
-
- /*
- * Avoid blocking other tasks for too long. It might even save
- * us from writing caches for block groups that are going to be
- * removed.
- */
- mutex_unlock(&trans->transaction->cache_write_mutex);
- mutex_lock(&trans->transaction->cache_write_mutex);
- }
- mutex_unlock(&trans->transaction->cache_write_mutex);
-
- /*
- * go through delayed refs for all the stuff we've just kicked off
- * and then loop back (just once)
- */
- ret = btrfs_run_delayed_refs(trans, 0);
- if (!ret && loops == 0) {
- loops++;
- spin_lock(&cur_trans->dirty_bgs_lock);
- list_splice_init(&cur_trans->dirty_bgs, &dirty);
- /*
- * dirty_bgs_lock protects us from concurrent block group
- * deletes too (not just cache_write_mutex).
- */
- if (!list_empty(&dirty)) {
- spin_unlock(&cur_trans->dirty_bgs_lock);
- goto again;
- }
- spin_unlock(&cur_trans->dirty_bgs_lock);
- } else if (ret < 0) {
- btrfs_cleanup_dirty_bgs(cur_trans, fs_info);
- }
-
- btrfs_free_path(path);
- return ret;
-}
-
-int btrfs_write_dirty_block_groups(struct btrfs_trans_handle *trans)
-{
- struct btrfs_fs_info *fs_info = trans->fs_info;
- struct btrfs_block_group_cache *cache;
- struct btrfs_transaction *cur_trans = trans->transaction;
- int ret = 0;
- int should_put;
- struct btrfs_path *path;
- struct list_head *io = &cur_trans->io_bgs;
- int num_started = 0;
-
- path = btrfs_alloc_path();
- if (!path)
- return -ENOMEM;
-
- /*
- * Even though we are in the critical section of the transaction commit,
- * we can still have concurrent tasks adding elements to this
- * transaction's list of dirty block groups. These tasks correspond to
- * endio free space workers started when writeback finishes for a
- * space cache, which run inode.c:btrfs_finish_ordered_io(), and can
- * allocate new block groups as a result of COWing nodes of the root
- * tree when updating the free space inode. The writeback for the space
- * caches is triggered by an earlier call to
- * btrfs_start_dirty_block_groups() and iterations of the following
- * loop.
- * Also we want to do the cache_save_setup first and then run the
- * delayed refs to make sure we have the best chance at doing this all
- * in one shot.
- */
- spin_lock(&cur_trans->dirty_bgs_lock);
- while (!list_empty(&cur_trans->dirty_bgs)) {
- cache = list_first_entry(&cur_trans->dirty_bgs,
- struct btrfs_block_group_cache,
- dirty_list);
-
- /*
- * this can happen if cache_save_setup re-dirties a block
- * group that is already under IO. Just wait for it to
- * finish and then do it all again
- */
- if (!list_empty(&cache->io_list)) {
- spin_unlock(&cur_trans->dirty_bgs_lock);
- list_del_init(&cache->io_list);
- btrfs_wait_cache_io(trans, cache, path);
- btrfs_put_block_group(cache);
- spin_lock(&cur_trans->dirty_bgs_lock);
- }
-
- /*
- * don't remove from the dirty list until after we've waited
- * on any pending IO
- */
- list_del_init(&cache->dirty_list);
- spin_unlock(&cur_trans->dirty_bgs_lock);
- should_put = 1;
-
- cache_save_setup(cache, trans, path);
-
- if (!ret)
- ret = btrfs_run_delayed_refs(trans,
- (unsigned long) -1);
-
- if (!ret && cache->disk_cache_state == BTRFS_DC_SETUP) {
- cache->io_ctl.inode = NULL;
- ret = btrfs_write_out_cache(trans, cache, path);
- if (ret == 0 && cache->io_ctl.inode) {
- num_started++;
- should_put = 0;
- list_add_tail(&cache->io_list, io);
- } else {
- /*
- * if we failed to write the cache, the
- * generation will be bad and life goes on
- */
- ret = 0;
- }
- }
- if (!ret) {
- ret = write_one_cache_group(trans, path, cache);
- /*
- * One of the free space endio workers might have
- * created a new block group while updating a free space
- * cache's inode (at inode.c:btrfs_finish_ordered_io())
- * and hasn't released its transaction handle yet, in
- * which case the new block group is still attached to
- * its transaction handle and its creation has not
- * finished yet (no block group item in the extent tree
- * yet, etc). If this is the case, wait for all free
- * space endio workers to finish and retry. This is a
- * a very rare case so no need for a more efficient and
- * complex approach.
- */
- if (ret == -ENOENT) {
- wait_event(cur_trans->writer_wait,
- atomic_read(&cur_trans->num_writers) == 1);
- ret = write_one_cache_group(trans, path, cache);
- }
- if (ret)
- btrfs_abort_transaction(trans, ret);
- }
-
- /* if its not on the io list, we need to put the block group */
- if (should_put)
- btrfs_put_block_group(cache);
- btrfs_delayed_refs_rsv_release(fs_info, 1);
- spin_lock(&cur_trans->dirty_bgs_lock);
- }
- spin_unlock(&cur_trans->dirty_bgs_lock);
-
- /*
- * Refer to the definition of io_bgs member for details why it's safe
- * to use it without any locking
- */
- while (!list_empty(io)) {
- cache = list_first_entry(io, struct btrfs_block_group_cache,
- io_list);
- list_del_init(&cache->io_list);
- btrfs_wait_cache_io(trans, cache, path);
- btrfs_put_block_group(cache);
- }
-
- btrfs_free_path(path);
- return ret;
-}
-
int btrfs_extent_readonly(struct btrfs_fs_info *fs_info, u64 bytenr)
{
struct btrfs_block_group_cache *block_group;
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