cow_file_range() works in an all-or-nothing way: if it fails to allocate an
extent for a part of the given region, it gives up all the region including
the successfully allocated parts. On cow_file_range(), run_delalloc_zoned()
writes data for the region only when it successfully allocate all the
region.
This all-or-nothing allocation and write-out are problematic when available
space in all the block groups are get tight with the active zone
restriction. btrfs_reserve_extent() try hard to utilize the left space in
the active block groups and gives up finally and fails with
-ENOSPC. However, if we send IOs for the successfully allocated region, we
can finish a zone and can continue on the rest of the allocation on a newly
allocated block group.
This patch implements the partial write-out for run_delalloc_zoned(). With
this patch applied, cow_file_range() returns -EAGAIN to tell the caller to
do something to progress the further allocation, and tells the successfully
allocated region with done_offset. Furthermore, the zoned extent allocator
returns -EAGAIN to tell cow_file_range() going back to the caller side.
Actually, we still need to wait for an IO to complete to continue the
allocation. The next patch implements that part.
CC: stable@xxxxxxxxxxxxxxx # 5.16+
Fixes: afba2bc036b0 ("btrfs: zoned: implement active zone tracking")
Signed-off-by: Naohiro Aota <naohiro.aota@xxxxxxx>
---
fs/btrfs/extent-tree.c | 10 +++++++
fs/btrfs/inode.c | 63 ++++++++++++++++++++++++++++++++----------
2 files changed, 59 insertions(+), 14 deletions(-)
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 5589e04eda0e..1b29b16f6736 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -3995,6 +3995,16 @@ static int can_allocate_chunk_zoned(struct btrfs_fs_info *fs_info,
if (ffe_ctl->max_extent_size >= ffe_ctl->min_alloc_size)
return -ENOSPC;
+ /*
+ * Even min_alloc_size is not left in any block groups. Since we cannot
+ * activate a new block group, allocating it may not help. Let's tell a
+ * caller to try again and hope it progress something by writing some
+ * parts of the region. That is only possible for data block groups,
+ * where a part of the region can be written.
+ */
+ if (ffe_ctl->flags & BTRFS_BLOCK_GROUP_DATA)
+ return -EAGAIN;
+
/*
* We cannot activate a new block group and no enough space left in any
* block groups. So, allocating a new block group may not help. But,
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 8ce937b0b014..681e2cb4dd9c 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -117,7 +117,8 @@ static int btrfs_truncate(struct inode *inode, bool skip_writeback);
static noinline int cow_file_range(struct btrfs_inode *inode,
struct page *locked_page,
u64 start, u64 end, int *page_started,
- unsigned long *nr_written, int unlock);
+ unsigned long *nr_written, int unlock,
+ u64 *done_offset);
static struct extent_map *create_io_em(struct btrfs_inode *inode, u64 start,
u64 len, u64 orig_start, u64 block_start,
u64 block_len, u64 orig_block_len,
@@ -921,7 +922,7 @@ static int submit_uncompressed_range(struct btrfs_inode *inode,
* can directly submit them without interruption.
*/
ret = cow_file_range(inode, locked_page, start, end, &page_started,
- &nr_written, 0);
+ &nr_written, 0, NULL);
/* Inline extent inserted, page gets unlocked and everything is done */
if (page_started) {
ret = 0;
@@ -1170,7 +1171,8 @@ static u64 get_extent_allocation_hint(struct btrfs_inode *inode, u64 start,
static noinline int cow_file_range(struct btrfs_inode *inode,
struct page *locked_page,
u64 start, u64 end, int *page_started,
- unsigned long *nr_written, int unlock)
+ unsigned long *nr_written, int unlock,
+ u64 *done_offset)
{
struct btrfs_root *root = inode->root;
struct btrfs_fs_info *fs_info = root->fs_info;
@@ -1363,6 +1365,21 @@ static noinline int cow_file_range(struct btrfs_inode *inode,
btrfs_dec_block_group_reservations(fs_info, ins.objectid);
btrfs_free_reserved_extent(fs_info, ins.objectid, ins.offset, 1);
out_unlock:
+ /*
+ * If done_offset is non-NULL and ret == -EAGAIN, we expect the
+ * caller to write out the successfully allocated region and retry.
+ */
+ if (done_offset && ret == -EAGAIN) {
+ if (orig_start < start)
+ *done_offset = start - 1;
+ else
+ *done_offset = start;
+ return ret;
+ } else if (ret == -EAGAIN) {
+ /* Convert to -ENOSPC since the caller cannot retry. */
+ ret = -ENOSPC;
+ }
+
/*
* Now, we have three regions to clean up:
*
@@ -1608,19 +1625,37 @@ static noinline int run_delalloc_zoned(struct btrfs_inode *inode,
u64 end, int *page_started,
unsigned long *nr_written)
{
+ u64 done_offset = end;
int ret;
+ bool locked_page_done = false;
- ret = cow_file_range(inode, locked_page, start, end, page_started,
- nr_written, 0);
- if (ret)
- return ret;
+ while (start <= end) {
+ ret = cow_file_range(inode, locked_page, start, end, page_started,
+ nr_written, 0, &done_offset);
+ if (ret && ret != -EAGAIN)
+ return ret;
- if (*page_started)
- return 0;
+ if (*page_started) {
+ ASSERT(ret == 0);
+ return 0;
+ }
+
+ if (ret == 0)
+ done_offset = end;
+
+ if (done_offset == start)
+ return -ENOSPC;
+
+ if (!locked_page_done) {
+ __set_page_dirty_nobuffers(locked_page);
+ account_page_redirty(locked_page);
+ }
+ locked_page_done = true;
+ extent_write_locked_range(&inode->vfs_inode, start, done_offset);
+
+ start = done_offset + 1;
+ }
- __set_page_dirty_nobuffers(locked_page);
- account_page_redirty(locked_page);
- extent_write_locked_range(&inode->vfs_inode, start, end);
*page_started = 1;
return 0;
@@ -1712,7 +1747,7 @@ static int fallback_to_cow(struct btrfs_inode *inode, struct page *locked_page,
}
return cow_file_range(inode, locked_page, start, end, page_started,
- nr_written, 1);
+ nr_written, 1, NULL);
}
struct can_nocow_file_extent_args {
@@ -2185,7 +2220,7 @@ int btrfs_run_delalloc_range(struct btrfs_inode *inode, struct page *locked_page
page_started, nr_written);
else
ret = cow_file_range(inode, locked_page, start, end,
- page_started, nr_written, 1);
+ page_started, nr_written, 1, NULL);
} else {
set_bit(BTRFS_INODE_HAS_ASYNC_EXTENT, &inode->runtime_flags);
ret = cow_file_range_async(inode, wbc, locked_page, start, end,
--
2.35.1
