btrfs: remove root usage from can_overcommit

can_overcommit using the root to determine the allocation profile
is the only use of a root in the call graph below reserve_metadata_bytes.

It turns out that we only need to know whether the allocation is for
the chunk root or not -- and we can pass that around as a bool instead.

This allows us to pull root usage out of the reservation path all the
way up to reserve_metadata_bytes itself, which uses it only to compare
against fs_info->chunk_root to set the bool.  In turn, this eliminates
a bunch of races where we use a particular root too early in the mount
process.

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Reviewed-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 47eb98f..87eab8f 100644 (file)
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -97,10 +97,11 @@ static int btrfs_free_reserved_bytes(struct btrfs_block_group_cache *cache,
                                     u64 num_bytes, int delalloc);
 static int block_rsv_use_bytes(struct btrfs_block_rsv *block_rsv,
                               u64 num_bytes);
-static int __reserve_metadata_bytes(struct btrfs_root *root,
+static int __reserve_metadata_bytes(struct btrfs_fs_info *fs_info,
                                    struct btrfs_space_info *space_info,
                                    u64 orig_bytes,
-                                   enum btrfs_reserve_flush_enum flush);
+                                   enum btrfs_reserve_flush_enum flush,
+                                   bool system_chunk);
 static void space_info_add_new_bytes(struct btrfs_fs_info *fs_info,
                                     struct btrfs_space_info *space_info,
                                     u64 num_bytes);
@@ -4628,11 +4629,11 @@ out:
        return ret;
 }
 
-static int can_overcommit(struct btrfs_root *root,
+static int can_overcommit(struct btrfs_fs_info *fs_info,
                          struct btrfs_space_info *space_info, u64 bytes,
-                         enum btrfs_reserve_flush_enum flush)
+                         enum btrfs_reserve_flush_enum flush,
+                         bool system_chunk)
 {
-       struct btrfs_fs_info *fs_info = root->fs_info;
        struct btrfs_block_rsv *global_rsv = &fs_info->global_block_rsv;
        u64 profile;
        u64 space_size;
@@ -4643,7 +4644,11 @@ static int can_overcommit(struct btrfs_root *root,
        if (space_info->flags & BTRFS_BLOCK_GROUP_DATA)
                return 0;
 
-       profile = get_alloc_profile_by_root(root, 0);
+       if (system_chunk)
+               profile = btrfs_system_alloc_profile(fs_info);
+       else
+               profile = btrfs_metadata_alloc_profile(fs_info);
+
        used = btrfs_space_info_used(space_info, false);
 
        /*
@@ -4728,10 +4733,9 @@ static inline int calc_reclaim_items_nr(struct btrfs_fs_info *fs_info,
 /*
  * shrink metadata reservation for delalloc
  */
-static void shrink_delalloc(struct btrfs_root *root, u64 to_reclaim, u64 orig,
-                           bool wait_ordered)
+static void shrink_delalloc(struct btrfs_fs_info *fs_info, u64 to_reclaim,
+                           u64 orig, bool wait_ordered)
 {
-       struct btrfs_fs_info *fs_info = root->fs_info;
        struct btrfs_block_rsv *block_rsv;
        struct btrfs_space_info *space_info;
        struct btrfs_trans_handle *trans;
@@ -4788,7 +4792,7 @@ skip_async:
                else
                        flush = BTRFS_RESERVE_NO_FLUSH;
                spin_lock(&space_info->lock);
-               if (can_overcommit(root, space_info, orig, flush)) {
+               if (can_overcommit(fs_info, space_info, orig, flush, false)) {
                        spin_unlock(&space_info->lock);
                        break;
                }
@@ -4898,7 +4902,7 @@ static int flush_space(struct btrfs_fs_info *fs_info,
                break;
        case FLUSH_DELALLOC:
        case FLUSH_DELALLOC_WAIT:
-               shrink_delalloc(root, num_bytes * 2, orig_bytes,
+               shrink_delalloc(fs_info, num_bytes * 2, orig_bytes,
                                state == FLUSH_DELALLOC_WAIT);
                break;
        case ALLOC_CHUNK:
@@ -4929,8 +4933,9 @@ static int flush_space(struct btrfs_fs_info *fs_info,
 }
 
 static inline u64
-btrfs_calc_reclaim_metadata_size(struct btrfs_root *root,
-                                struct btrfs_space_info *space_info)
+btrfs_calc_reclaim_metadata_size(struct btrfs_fs_info *fs_info,
+                                struct btrfs_space_info *space_info,
+                                bool system_chunk)
 {
        struct reserve_ticket *ticket;
        u64 used;
@@ -4945,14 +4950,15 @@ btrfs_calc_reclaim_metadata_size(struct btrfs_root *root,
                return to_reclaim;
 
        to_reclaim = min_t(u64, num_online_cpus() * SZ_1M, SZ_16M);
-       if (can_overcommit(root, space_info, to_reclaim,
-                          BTRFS_RESERVE_FLUSH_ALL))
+       if (can_overcommit(fs_info, space_info, to_reclaim,
+                          BTRFS_RESERVE_FLUSH_ALL, system_chunk))
                return 0;
 
        used = space_info->bytes_used + space_info->bytes_reserved +
               space_info->bytes_pinned + space_info->bytes_readonly +
               space_info->bytes_may_use;
-       if (can_overcommit(root, space_info, SZ_1M, BTRFS_RESERVE_FLUSH_ALL))
+       if (can_overcommit(fs_info, space_info, SZ_1M,
+                          BTRFS_RESERVE_FLUSH_ALL, system_chunk))
                expected = div_factor_fine(space_info->total_bytes, 95);
        else
                expected = div_factor_fine(space_info->total_bytes, 90);
@@ -4966,17 +4972,18 @@ btrfs_calc_reclaim_metadata_size(struct btrfs_root *root,
        return to_reclaim;
 }
 
-static inline int need_do_async_reclaim(struct btrfs_space_info *space_info,
-                                       struct btrfs_root *root, u64 used)
+static inline int need_do_async_reclaim(struct btrfs_fs_info *fs_info,
+                                       struct btrfs_space_info *space_info,
+                                       u64 used, bool system_chunk)
 {
-       struct btrfs_fs_info *fs_info = root->fs_info;
        u64 thresh = div_factor_fine(space_info->total_bytes, 98);
 
        /* If we're just plain full then async reclaim just slows us down. */
        if ((space_info->bytes_used + space_info->bytes_reserved) >= thresh)
                return 0;
 
-       if (!btrfs_calc_reclaim_metadata_size(root, space_info))
+       if (!btrfs_calc_reclaim_metadata_size(fs_info, space_info,
+                                             system_chunk))
                return 0;
 
        return (used >= thresh && !btrfs_fs_closing(fs_info) &&
@@ -5013,8 +5020,8 @@ static void btrfs_async_reclaim_metadata_space(struct work_struct *work)
        space_info = __find_space_info(fs_info, BTRFS_BLOCK_GROUP_METADATA);
 
        spin_lock(&space_info->lock);
-       to_reclaim = btrfs_calc_reclaim_metadata_size(fs_info->fs_root,
-                                                     space_info);
+       to_reclaim = btrfs_calc_reclaim_metadata_size(fs_info, space_info,
+                                                     false);
        if (!to_reclaim) {
                space_info->flush = 0;
                spin_unlock(&space_info->lock);
@@ -5036,8 +5043,9 @@ static void btrfs_async_reclaim_metadata_space(struct work_struct *work)
                        spin_unlock(&space_info->lock);
                        return;
                }
-               to_reclaim = btrfs_calc_reclaim_metadata_size(fs_info->fs_root,
-                                                             space_info);
+               to_reclaim = btrfs_calc_reclaim_metadata_size(fs_info,
+                                                             space_info,
+                                                             false);
                ticket = list_first_entry(&space_info->tickets,
                                          struct reserve_ticket, list);
                if (last_tickets_id == space_info->tickets_id) {
@@ -5075,8 +5083,8 @@ static void priority_reclaim_metadata_space(struct btrfs_fs_info *fs_info,
        int flush_state = FLUSH_DELAYED_ITEMS_NR;
 
        spin_lock(&space_info->lock);
-       to_reclaim = btrfs_calc_reclaim_metadata_size(fs_info->extent_root,
-                                                     space_info);
+       to_reclaim = btrfs_calc_reclaim_metadata_size(fs_info, space_info,
+                                                     false);
        if (!to_reclaim) {
                spin_unlock(&space_info->lock);
                return;
@@ -5155,12 +5163,12 @@ static int wait_reserve_ticket(struct btrfs_fs_info *fs_info,
  * regain reservations will be made and this will fail if there is not enough
  * space already.
  */
-static int __reserve_metadata_bytes(struct btrfs_root *root,
+static int __reserve_metadata_bytes(struct btrfs_fs_info *fs_info,
                                    struct btrfs_space_info *space_info,
                                    u64 orig_bytes,
-                                   enum btrfs_reserve_flush_enum flush)
+                                   enum btrfs_reserve_flush_enum flush,
+                                   bool system_chunk)
 {
-       struct btrfs_fs_info *fs_info = root->fs_info;
        struct reserve_ticket ticket;
        u64 used;
        int ret = 0;
@@ -5182,7 +5190,8 @@ static int __reserve_metadata_bytes(struct btrfs_root *root,
                trace_btrfs_space_reservation(fs_info, "space_info",
                                              space_info->flags, orig_bytes, 1);
                ret = 0;
-       } else if (can_overcommit(root, space_info, orig_bytes, flush)) {
+       } else if (can_overcommit(fs_info, space_info, orig_bytes, flush,
+                                 system_chunk)) {
                space_info->bytes_may_use += orig_bytes;
                trace_btrfs_space_reservation(fs_info, "space_info",
                                              space_info->flags, orig_bytes, 1);
@@ -5209,7 +5218,7 @@ static int __reserve_metadata_bytes(struct btrfs_root *root,
                                                          orig_bytes, flush,
                                                          "enospc");
                                queue_work(system_unbound_wq,
-                                          &root->fs_info->async_reclaim_work);
+                                          &fs_info->async_reclaim_work);
                        }
                } else {
                        list_add_tail(&ticket.list,
@@ -5223,7 +5232,8 @@ static int __reserve_metadata_bytes(struct btrfs_root *root,
                 * the async reclaim as we will panic.
                 */
                if (!test_bit(BTRFS_FS_LOG_RECOVERING, &fs_info->flags) &&
-                   need_do_async_reclaim(space_info, root, used) &&
+                   need_do_async_reclaim(fs_info, space_info,
+                                         used, system_chunk) &&
                    !work_busy(&fs_info->async_reclaim_work)) {
                        trace_btrfs_trigger_flush(fs_info, space_info->flags,
                                                  orig_bytes, flush, "preempt");
@@ -5281,9 +5291,10 @@ static int reserve_metadata_bytes(struct btrfs_root *root,
        struct btrfs_fs_info *fs_info = root->fs_info;
        struct btrfs_block_rsv *global_rsv = &fs_info->global_block_rsv;
        int ret;
+       bool system_chunk = (root == fs_info->chunk_root);
 
-       ret = __reserve_metadata_bytes(root, block_rsv->space_info, orig_bytes,
-                                      flush);
+       ret = __reserve_metadata_bytes(fs_info, block_rsv->space_info,
+                                      orig_bytes, flush, system_chunk);
        if (ret == -ENOSPC &&
            unlikely(root->orphan_cleanup_state == ORPHAN_CLEANUP_STARTED)) {
                if (block_rsv != global_rsv &&
@@ -5406,8 +5417,7 @@ again:
                 * adding the ticket space would be a double count.
                 */
                if (check_overcommit &&
-                   !can_overcommit(fs_info->extent_root, space_info, 0,
-                                   flush))
+                   !can_overcommit(fs_info, space_info, 0, flush, false))
                        break;
                if (num_bytes >= ticket->bytes) {
                        list_del_init(&ticket->list);