btrfs: extent-tree: Detect bytes_may_use underflow earlier

Although we have space_info::bytes_may_use underflow detection in
btrfs_free_reserved_data_space_noquota(), we have more callers who are
subtracting number from space_info::bytes_may_use.

So instead of doing underflow detection for every caller, introduce a
new wrapper update_bytes_may_use() to replace open coded bytes_may_use
modifiers.

This also introduce a macro to declare more wrappers, but currently
space_info::bytes_may_use is the mostly interesting one.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Lu Fengqi <lufq.fnst@cn.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index a1febf1..395d9d5 100644 (file)
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -51,6 +51,23 @@ enum {
        CHUNK_ALLOC_FORCE = 2,
 };
 
+/*
+ * Declare a helper function to detect underflow of various space info members
+ */
+#define DECLARE_SPACE_INFO_UPDATE(name)                                        \
+static inline void update_##name(struct btrfs_space_info *sinfo,       \
+                                s64 bytes)                             \
+{                                                                      \
+       if (bytes < 0 && sinfo->name < -bytes) {                        \
+               WARN_ON(1);                                             \
+               sinfo->name = 0;                                        \
+               return;                                                 \
+       }                                                               \
+       sinfo->name += bytes;                                           \
+}
+
+DECLARE_SPACE_INFO_UPDATE(bytes_may_use);
+
 static int __btrfs_free_extent(struct btrfs_trans_handle *trans,
                               struct btrfs_delayed_ref_node *node, u64 parent,
                               u64 root_objectid, u64 owner_objectid,
@@ -4256,7 +4273,7 @@ commit_trans:
                                              data_sinfo->flags, bytes, 1);
                return -ENOSPC;
        }
-       data_sinfo->bytes_may_use += bytes;
+       update_bytes_may_use(data_sinfo, bytes);
        trace_btrfs_space_reservation(fs_info, "space_info",
                                      data_sinfo->flags, bytes, 1);
        spin_unlock(&data_sinfo->lock);
@@ -4309,10 +4326,7 @@ void btrfs_free_reserved_data_space_noquota(struct inode *inode, u64 start,
 
        data_sinfo = fs_info->data_sinfo;
        spin_lock(&data_sinfo->lock);
-       if (WARN_ON(data_sinfo->bytes_may_use < len))
-               data_sinfo->bytes_may_use = 0;
-       else
-               data_sinfo->bytes_may_use -= len;
+       update_bytes_may_use(data_sinfo, -len);
        trace_btrfs_space_reservation(fs_info, "space_info",
                                      data_sinfo->flags, len, 0);
        spin_unlock(&data_sinfo->lock);
@@ -5108,7 +5122,7 @@ static int wait_reserve_ticket(struct btrfs_fs_info *fs_info,
                list_del_init(&ticket->list);
        if (ticket->bytes && ticket->bytes < orig_bytes) {
                u64 num_bytes = orig_bytes - ticket->bytes;
-               space_info->bytes_may_use -= num_bytes;
+               update_bytes_may_use(space_info, -num_bytes);
                trace_btrfs_space_reservation(fs_info, "space_info",
                                              space_info->flags, num_bytes, 0);
        }
@@ -5154,13 +5168,13 @@ static int __reserve_metadata_bytes(struct btrfs_fs_info *fs_info,
         * If not things get more complicated.
         */
        if (used + orig_bytes <= space_info->total_bytes) {
-               space_info->bytes_may_use += orig_bytes;
+               update_bytes_may_use(space_info, orig_bytes);
                trace_btrfs_space_reservation(fs_info, "space_info",
                                              space_info->flags, orig_bytes, 1);
                ret = 0;
        } else if (can_overcommit(fs_info, space_info, orig_bytes, flush,
                                  system_chunk)) {
-               space_info->bytes_may_use += orig_bytes;
+               update_bytes_may_use(space_info, orig_bytes);
                trace_btrfs_space_reservation(fs_info, "space_info",
                                              space_info->flags, orig_bytes, 1);
                ret = 0;
@@ -5223,7 +5237,7 @@ static int __reserve_metadata_bytes(struct btrfs_fs_info *fs_info,
        if (ticket.bytes) {
                if (ticket.bytes < orig_bytes) {
                        u64 num_bytes = orig_bytes - ticket.bytes;
-                       space_info->bytes_may_use -= num_bytes;
+                       update_bytes_may_use(space_info, -num_bytes);
                        trace_btrfs_space_reservation(fs_info, "space_info",
                                                      space_info->flags,
                                                      num_bytes, 0);
@@ -5407,7 +5421,7 @@ again:
                flush = BTRFS_RESERVE_FLUSH_ALL;
                goto again;
        }
-       space_info->bytes_may_use -= num_bytes;
+       update_bytes_may_use(space_info, -num_bytes);
        trace_btrfs_space_reservation(fs_info, "space_info",
                                      space_info->flags, num_bytes, 0);
        spin_unlock(&space_info->lock);
@@ -5435,7 +5449,7 @@ again:
                                                      ticket->bytes, 1);
                        list_del_init(&ticket->list);
                        num_bytes -= ticket->bytes;
-                       space_info->bytes_may_use += ticket->bytes;
+                       update_bytes_may_use(space_info, ticket->bytes);
                        ticket->bytes = 0;
                        space_info->tickets_id++;
                        wake_up(&ticket->wait);
@@ -5443,7 +5457,7 @@ again:
                        trace_btrfs_space_reservation(fs_info, "space_info",
                                                      space_info->flags,
                                                      num_bytes, 1);
-                       space_info->bytes_may_use += num_bytes;
+                       update_bytes_may_use(space_info, num_bytes);
                        ticket->bytes -= num_bytes;
                        num_bytes = 0;
                }
@@ -5750,14 +5764,14 @@ static void update_global_block_rsv(struct btrfs_fs_info *fs_info)
                        num_bytes = min(num_bytes,
                                        block_rsv->size - block_rsv->reserved);
                        block_rsv->reserved += num_bytes;
-                       sinfo->bytes_may_use += num_bytes;
+                       update_bytes_may_use(sinfo, num_bytes);
                        trace_btrfs_space_reservation(fs_info, "space_info",
                                                      sinfo->flags, num_bytes,
                                                      1);
                }
        } else if (block_rsv->reserved > block_rsv->size) {
                num_bytes = block_rsv->reserved - block_rsv->size;
-               sinfo->bytes_may_use -= num_bytes;
+               update_bytes_may_use(sinfo, -num_bytes);
                trace_btrfs_space_reservation(fs_info, "space_info",
                                      sinfo->flags, num_bytes, 0);
                block_rsv->reserved = block_rsv->size;
@@ -6431,7 +6445,7 @@ static int btrfs_add_reserved_bytes(struct btrfs_block_group_cache *cache,
        } else {
                cache->reserved += num_bytes;
                space_info->bytes_reserved += num_bytes;
-               space_info->bytes_may_use -= ram_bytes;
+               update_bytes_may_use(space_info, -ram_bytes);
                if (delalloc)
                        cache->delalloc_bytes += num_bytes;
        }
@@ -6608,7 +6622,7 @@ static int unpin_extent_range(struct btrfs_fs_info *fs_info,
                                to_add = min(len, global_rsv->size -
                                             global_rsv->reserved);
                                global_rsv->reserved += to_add;
-                               space_info->bytes_may_use += to_add;
+                               update_bytes_may_use(space_info, to_add);
                                if (global_rsv->reserved >= global_rsv->size)
                                        global_rsv->full = 1;
                                trace_btrfs_space_reservation(fs_info,