Btrfs: use bytes_may_use for all ENOSPC reservations
We have been using bytes_reserved for metadata reservations, which is wrong
since we use that to keep track of outstanding reservations from the allocator.
This resulted in us doing a lot of silly things to make sure we don't allocate a
bunch of metadata chunks since we never had a real view of how much space was
actually in use by metadata.
This passes Arne's enospc test and xfstests as well as my own enospc tests.
Hopefully this will get us moving in the right direction. Thanks,
Signed-off-by: Josef Bacik <josef@redhat.com>
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 03edac4..fbe6278 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -52,6 +52,21 @@
CHUNK_ALLOC_LIMITED = 2,
};
+/*
+ * Control how reservations are dealt with.
+ *
+ * RESERVE_FREE - freeing a reservation.
+ * RESERVE_ALLOC - allocating space and we need to update bytes_may_use for
+ * ENOSPC accounting
+ * RESERVE_ALLOC_NO_ACCOUNT - allocating space and we should not update
+ * bytes_may_use as the ENOSPC accounting is done elsewhere
+ */
+enum {
+ RESERVE_FREE = 0,
+ RESERVE_ALLOC = 1,
+ RESERVE_ALLOC_NO_ACCOUNT = 2,
+};
+
static int update_block_group(struct btrfs_trans_handle *trans,
struct btrfs_root *root,
u64 bytenr, u64 num_bytes, int alloc);
@@ -81,6 +96,8 @@
struct btrfs_key *key);
static void dump_space_info(struct btrfs_space_info *info, u64 bytes,
int dump_block_groups);
+static int btrfs_update_reserved_bytes(struct btrfs_block_group_cache *cache,
+ u64 num_bytes, int reserve);
static noinline int
block_group_cache_done(struct btrfs_block_group_cache *cache)
@@ -3128,9 +3145,7 @@
}
/*
- * called when we are clearing an delalloc extent from the
- * inode's io_tree or there was an error for whatever reason
- * after calling btrfs_check_data_free_space
+ * Called if we need to clear a data reservation for this inode.
*/
void btrfs_free_reserved_data_space(struct inode *inode, u64 bytes)
{
@@ -3163,6 +3178,7 @@
struct btrfs_space_info *sinfo, u64 alloc_bytes,
int force)
{
+ struct btrfs_block_rsv *global_rsv = &root->fs_info->global_block_rsv;
u64 num_bytes = sinfo->total_bytes - sinfo->bytes_readonly;
u64 num_allocated = sinfo->bytes_used + sinfo->bytes_reserved;
u64 thresh;
@@ -3171,6 +3187,13 @@
return 1;
/*
+ * We need to take into account the global rsv because for all intents
+ * and purposes it's used space. Don't worry about locking the
+ * global_rsv, it doesn't change except when the transaction commits.
+ */
+ num_allocated += global_rsv->size;
+
+ /*
* in limited mode, we want to have some free space up to
* about 1% of the FS size.
*/
@@ -3317,7 +3340,7 @@
space_info = block_rsv->space_info;
smp_mb();
- reserved = space_info->bytes_reserved;
+ reserved = space_info->bytes_may_use;
progress = space_info->reservation_progress;
if (reserved == 0)
@@ -3341,9 +3364,9 @@
writeback_inodes_sb_nr_if_idle(root->fs_info->sb, nr_pages);
spin_lock(&space_info->lock);
- if (reserved > space_info->bytes_reserved)
- reclaimed += reserved - space_info->bytes_reserved;
- reserved = space_info->bytes_reserved;
+ if (reserved > space_info->bytes_may_use)
+ reclaimed += reserved - space_info->bytes_may_use;
+ reserved = space_info->bytes_may_use;
spin_unlock(&space_info->lock);
loops++;
@@ -3401,7 +3424,6 @@
int ret = 0;
bool committed = false;
bool flushing = false;
-
again:
ret = 0;
spin_lock(&space_info->lock);
@@ -3443,7 +3465,7 @@
if (unused <= space_info->total_bytes) {
unused = space_info->total_bytes - unused;
if (unused >= num_bytes) {
- space_info->bytes_reserved += orig_bytes;
+ space_info->bytes_may_use += orig_bytes;
ret = 0;
} else {
/*
@@ -3614,7 +3636,7 @@
}
if (num_bytes) {
spin_lock(&space_info->lock);
- space_info->bytes_reserved -= num_bytes;
+ space_info->bytes_may_use -= num_bytes;
space_info->reservation_progress++;
spin_unlock(&space_info->lock);
}
@@ -3825,12 +3847,12 @@
if (sinfo->total_bytes > num_bytes) {
num_bytes = sinfo->total_bytes - num_bytes;
block_rsv->reserved += num_bytes;
- sinfo->bytes_reserved += num_bytes;
+ sinfo->bytes_may_use += num_bytes;
}
if (block_rsv->reserved >= block_rsv->size) {
num_bytes = block_rsv->reserved - block_rsv->size;
- sinfo->bytes_reserved -= num_bytes;
+ sinfo->bytes_may_use -= num_bytes;
sinfo->reservation_progress++;
block_rsv->reserved = block_rsv->size;
block_rsv->full = 1;
@@ -4133,7 +4155,6 @@
btrfs_set_block_group_used(&cache->item, old_val);
cache->reserved -= num_bytes;
cache->space_info->bytes_reserved -= num_bytes;
- cache->space_info->reservation_progress++;
cache->space_info->bytes_used += num_bytes;
cache->space_info->disk_used += num_bytes * factor;
spin_unlock(&cache->lock);
@@ -4185,7 +4206,6 @@
if (reserved) {
cache->reserved -= num_bytes;
cache->space_info->bytes_reserved -= num_bytes;
- cache->space_info->reservation_progress++;
}
spin_unlock(&cache->lock);
spin_unlock(&cache->space_info->lock);
@@ -4212,46 +4232,55 @@
return 0;
}
-/*
- * update size of reserved extents. this function may return -EAGAIN
- * if 'reserve' is true or 'sinfo' is false.
+/**
+ * btrfs_update_reserved_bytes - update the block_group and space info counters
+ * @cache: The cache we are manipulating
+ * @num_bytes: The number of bytes in question
+ * @reserve: One of the reservation enums
+ *
+ * This is called by the allocator when it reserves space, or by somebody who is
+ * freeing space that was never actually used on disk. For example if you
+ * reserve some space for a new leaf in transaction A and before transaction A
+ * commits you free that leaf, you call this with reserve set to 0 in order to
+ * clear the reservation.
+ *
+ * Metadata reservations should be called with RESERVE_ALLOC so we do the proper
+ * ENOSPC accounting. For data we handle the reservation through clearing the
+ * delalloc bits in the io_tree. We have to do this since we could end up
+ * allocating less disk space for the amount of data we have reserved in the
+ * case of compression.
+ *
+ * If this is a reservation and the block group has become read only we cannot
+ * make the reservation and return -EAGAIN, otherwise this function always
+ * succeeds.
*/
-int btrfs_update_reserved_bytes(struct btrfs_block_group_cache *cache,
- u64 num_bytes, int reserve, int sinfo)
+static int btrfs_update_reserved_bytes(struct btrfs_block_group_cache *cache,
+ u64 num_bytes, int reserve)
{
+ struct btrfs_space_info *space_info = cache->space_info;
int ret = 0;
- if (sinfo) {
- struct btrfs_space_info *space_info = cache->space_info;
- spin_lock(&space_info->lock);
- spin_lock(&cache->lock);
- if (reserve) {
- if (cache->ro) {
- ret = -EAGAIN;
- } else {
- cache->reserved += num_bytes;
- space_info->bytes_reserved += num_bytes;
- }
- } else {
- if (cache->ro)
- space_info->bytes_readonly += num_bytes;
- cache->reserved -= num_bytes;
- space_info->bytes_reserved -= num_bytes;
- space_info->reservation_progress++;
- }
- spin_unlock(&cache->lock);
- spin_unlock(&space_info->lock);
- } else {
- spin_lock(&cache->lock);
+ spin_lock(&space_info->lock);
+ spin_lock(&cache->lock);
+ if (reserve != RESERVE_FREE) {
if (cache->ro) {
ret = -EAGAIN;
} else {
- if (reserve)
- cache->reserved += num_bytes;
- else
- cache->reserved -= num_bytes;
+ cache->reserved += num_bytes;
+ space_info->bytes_reserved += num_bytes;
+ if (reserve == RESERVE_ALLOC) {
+ BUG_ON(space_info->bytes_may_use < num_bytes);
+ space_info->bytes_may_use -= num_bytes;
+ }
}
- spin_unlock(&cache->lock);
+ } else {
+ if (cache->ro)
+ space_info->bytes_readonly += num_bytes;
+ cache->reserved -= num_bytes;
+ space_info->bytes_reserved -= num_bytes;
+ space_info->reservation_progress++;
}
+ spin_unlock(&cache->lock);
+ spin_unlock(&space_info->lock);
return ret;
}
@@ -4322,7 +4351,7 @@
} else if (cache->reserved_pinned > 0) {
len = min(len, cache->reserved_pinned);
cache->reserved_pinned -= len;
- cache->space_info->bytes_reserved += len;
+ cache->space_info->bytes_may_use += len;
}
spin_unlock(&cache->lock);
spin_unlock(&cache->space_info->lock);
@@ -4701,27 +4730,8 @@
WARN_ON(test_bit(EXTENT_BUFFER_DIRTY, &buf->bflags));
btrfs_add_free_space(cache, buf->start, buf->len);
- ret = btrfs_update_reserved_bytes(cache, buf->len, 0, 0);
- if (ret == -EAGAIN) {
- /* block group became read-only */
- btrfs_update_reserved_bytes(cache, buf->len, 0, 1);
- goto out;
- }
+ btrfs_update_reserved_bytes(cache, buf->len, RESERVE_FREE);
- ret = 1;
- spin_lock(&block_rsv->lock);
- if (block_rsv->reserved < block_rsv->size) {
- block_rsv->reserved += buf->len;
- ret = 0;
- }
- spin_unlock(&block_rsv->lock);
-
- if (ret) {
- spin_lock(&cache->space_info->lock);
- cache->space_info->bytes_reserved -= buf->len;
- cache->space_info->reservation_progress++;
- spin_unlock(&cache->space_info->lock);
- }
goto out;
}
pin:
@@ -4881,6 +4891,8 @@
int last_ptr_loop = 0;
int loop = 0;
int index = 0;
+ int alloc_type = (data & BTRFS_BLOCK_GROUP_DATA) ?
+ RESERVE_ALLOC_NO_ACCOUNT : RESERVE_ALLOC;
bool found_uncached_bg = false;
bool failed_cluster_refill = false;
bool failed_alloc = false;
@@ -5200,8 +5212,8 @@
search_start - offset);
BUG_ON(offset > search_start);
- ret = btrfs_update_reserved_bytes(block_group, num_bytes, 1,
- (data & BTRFS_BLOCK_GROUP_DATA));
+ ret = btrfs_update_reserved_bytes(block_group, num_bytes,
+ alloc_type);
if (ret == -EAGAIN) {
btrfs_add_free_space(block_group, offset, num_bytes);
goto loop;
@@ -5323,7 +5335,8 @@
int index = 0;
spin_lock(&info->lock);
- printk(KERN_INFO "space_info has %llu free, is %sfull\n",
+ printk(KERN_INFO "space_info %llu has %llu free, is %sfull\n",
+ (unsigned long long)info->flags,
(unsigned long long)(info->total_bytes - info->bytes_used -
info->bytes_pinned - info->bytes_reserved -
info->bytes_readonly),
@@ -5425,7 +5438,7 @@
ret = btrfs_discard_extent(root, start, len, NULL);
btrfs_add_free_space(cache, start, len);
- btrfs_update_reserved_bytes(cache, len, 0, 1);
+ btrfs_update_reserved_bytes(cache, len, RESERVE_FREE);
btrfs_put_block_group(cache);
trace_btrfs_reserved_extent_free(root, start, len);
@@ -5628,7 +5641,8 @@
put_caching_control(caching_ctl);
}
- ret = btrfs_update_reserved_bytes(block_group, ins->offset, 1, 1);
+ ret = btrfs_update_reserved_bytes(block_group, ins->offset,
+ RESERVE_ALLOC_NO_ACCOUNT);
BUG_ON(ret);
btrfs_put_block_group(block_group);
ret = alloc_reserved_file_extent(trans, root, 0, root_objectid,
@@ -6594,7 +6608,7 @@
cache->reserved_pinned + num_bytes + min_allocable_bytes <=
sinfo->total_bytes) {
sinfo->bytes_readonly += num_bytes;
- sinfo->bytes_reserved += cache->reserved_pinned;
+ sinfo->bytes_may_use += cache->reserved_pinned;
cache->reserved_pinned = 0;
cache->ro = 1;
ret = 0;
@@ -6962,7 +6976,8 @@
struct btrfs_space_info,
list);
if (space_info->bytes_pinned > 0 ||
- space_info->bytes_reserved > 0) {
+ space_info->bytes_reserved > 0 ||
+ space_info->bytes_may_use > 0) {
WARN_ON(1);
dump_space_info(space_info, 0, 0);
}
