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-rw-r--r--fs/btrfs/block-group.c58
-rw-r--r--fs/btrfs/block-group.h5
-rw-r--r--fs/btrfs/inode.c26
3 files changed, 60 insertions, 29 deletions
diff --git a/fs/btrfs/block-group.c b/fs/btrfs/block-group.c
index db112a01d711..9739f3e8230a 100644
--- a/fs/btrfs/block-group.c
+++ b/fs/btrfs/block-group.c
@@ -284,42 +284,66 @@ struct btrfs_block_group *btrfs_next_block_group(
return cache;
}
-bool btrfs_inc_nocow_writers(struct btrfs_fs_info *fs_info, u64 bytenr)
+/**
+ * Check if we can do a NOCOW write for a given extent.
+ *
+ * @fs_info: The filesystem information object.
+ * @bytenr: Logical start address of the extent.
+ *
+ * Check if we can do a NOCOW write for the given extent, and increments the
+ * number of NOCOW writers in the block group that contains the extent, as long
+ * as the block group exists and it's currently not in read-only mode.
+ *
+ * Returns: A non-NULL block group pointer if we can do a NOCOW write, the caller
+ * is responsible for calling btrfs_dec_nocow_writers() later.
+ *
+ * Or NULL if we can not do a NOCOW write
+ */
+struct btrfs_block_group *btrfs_inc_nocow_writers(struct btrfs_fs_info *fs_info,
+ u64 bytenr)
{
struct btrfs_block_group *bg;
- bool ret = true;
+ bool can_nocow = true;
bg = btrfs_lookup_block_group(fs_info, bytenr);
if (!bg)
- return false;
+ return NULL;
spin_lock(&bg->lock);
if (bg->ro)
- ret = false;
+ can_nocow = false;
else
atomic_inc(&bg->nocow_writers);
spin_unlock(&bg->lock);
- /* No put on block group, done by btrfs_dec_nocow_writers */
- if (!ret)
+ if (!can_nocow) {
btrfs_put_block_group(bg);
+ return NULL;
+ }
- return ret;
+ /* No put on block group, done by btrfs_dec_nocow_writers(). */
+ return bg;
}
-void btrfs_dec_nocow_writers(struct btrfs_fs_info *fs_info, u64 bytenr)
+/**
+ * Decrement the number of NOCOW writers in a block group.
+ *
+ * @bg: The block group.
+ *
+ * This is meant to be called after a previous call to btrfs_inc_nocow_writers(),
+ * and on the block group returned by that call. Typically this is called after
+ * creating an ordered extent for a NOCOW write, to prevent races with scrub and
+ * relocation.
+ *
+ * After this call, the caller should not use the block group anymore. It it wants
+ * to use it, then it should get a reference on it before calling this function.
+ */
+void btrfs_dec_nocow_writers(struct btrfs_block_group *bg)
{
- struct btrfs_block_group *bg;
-
- bg = btrfs_lookup_block_group(fs_info, bytenr);
- ASSERT(bg);
if (atomic_dec_and_test(&bg->nocow_writers))
wake_up_var(&bg->nocow_writers);
- /*
- * Once for our lookup and once for the lookup done by a previous call
- * to btrfs_inc_nocow_writers()
- */
- btrfs_put_block_group(bg);
+
+ /* For the lookup done by a previous call to btrfs_inc_nocow_writers(). */
btrfs_put_block_group(bg);
}
diff --git a/fs/btrfs/block-group.h b/fs/btrfs/block-group.h
index e8308f2ad07d..c9bf01dd10e8 100644
--- a/fs/btrfs/block-group.h
+++ b/fs/btrfs/block-group.h
@@ -254,8 +254,9 @@ void btrfs_put_block_group(struct btrfs_block_group *cache);
void btrfs_dec_block_group_reservations(struct btrfs_fs_info *fs_info,
const u64 start);
void btrfs_wait_block_group_reservations(struct btrfs_block_group *bg);
-bool btrfs_inc_nocow_writers(struct btrfs_fs_info *fs_info, u64 bytenr);
-void btrfs_dec_nocow_writers(struct btrfs_fs_info *fs_info, u64 bytenr);
+struct btrfs_block_group *btrfs_inc_nocow_writers(struct btrfs_fs_info *fs_info,
+ u64 bytenr);
+void btrfs_dec_nocow_writers(struct btrfs_block_group *bg);
void btrfs_wait_nocow_writers(struct btrfs_block_group *bg);
void btrfs_wait_block_group_cache_progress(struct btrfs_block_group *cache,
u64 num_bytes);
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index a1504cdbab7a..44b7c9a7c84d 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -1773,6 +1773,7 @@ static noinline int run_delalloc_nocow(struct btrfs_inode *inode,
int ret;
bool check_prev = true;
u64 ino = btrfs_ino(inode);
+ struct btrfs_block_group *bg;
bool nocow = false;
struct can_nocow_file_extent_args nocow_args = { 0 };
@@ -1901,7 +1902,8 @@ next_slot:
}
ret = 0;
- if (btrfs_inc_nocow_writers(fs_info, nocow_args.disk_bytenr))
+ bg = btrfs_inc_nocow_writers(fs_info, nocow_args.disk_bytenr);
+ if (bg)
nocow = true;
out_check:
/*
@@ -1977,9 +1979,10 @@ out_check:
goto error;
}
- if (nocow)
- btrfs_dec_nocow_writers(fs_info, nocow_args.disk_bytenr);
- nocow = false;
+ if (nocow) {
+ btrfs_dec_nocow_writers(bg);
+ nocow = false;
+ }
if (btrfs_is_data_reloc_root(root))
/*
@@ -2023,7 +2026,7 @@ out_check:
error:
if (nocow)
- btrfs_dec_nocow_writers(fs_info, nocow_args.disk_bytenr);
+ btrfs_dec_nocow_writers(bg);
if (ret && cur_offset < end)
extent_clear_unlock_delalloc(inode, cur_offset, end,
@@ -7417,6 +7420,7 @@ static int btrfs_get_blocks_direct_write(struct extent_map **map,
struct extent_map *em = *map;
int type;
u64 block_start, orig_start, orig_block_len, ram_bytes;
+ struct btrfs_block_group *bg;
bool can_nocow = false;
bool space_reserved = false;
u64 prev_len;
@@ -7442,9 +7446,11 @@ static int btrfs_get_blocks_direct_write(struct extent_map **map,
block_start = em->block_start + (start - em->start);
if (can_nocow_extent(inode, start, &len, &orig_start,
- &orig_block_len, &ram_bytes, false) == 1 &&
- btrfs_inc_nocow_writers(fs_info, block_start))
- can_nocow = true;
+ &orig_block_len, &ram_bytes, false) == 1) {
+ bg = btrfs_inc_nocow_writers(fs_info, block_start);
+ if (bg)
+ can_nocow = true;
+ }
}
prev_len = len;
@@ -7458,7 +7464,7 @@ static int btrfs_get_blocks_direct_write(struct extent_map **map,
/* Our caller expects us to free the input extent map. */
free_extent_map(em);
*map = NULL;
- btrfs_dec_nocow_writers(fs_info, block_start);
+ btrfs_dec_nocow_writers(bg);
if (nowait && (ret == -ENOSPC || ret == -EDQUOT))
ret = -EAGAIN;
goto out;
@@ -7469,7 +7475,7 @@ static int btrfs_get_blocks_direct_write(struct extent_map **map,
orig_start, block_start,
len, orig_block_len,
ram_bytes, type);
- btrfs_dec_nocow_writers(fs_info, block_start);
+ btrfs_dec_nocow_writers(bg);
if (type == BTRFS_ORDERED_PREALLOC) {
free_extent_map(em);
*map = em = em2;
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