On Tue, Feb 21, 2017 at 04:06:59PM +0800, Qu Wenruo wrote:
> If run btrfs/125 with nospace_cache or space_cache=v2 mount option,
> btrfs will block with the following backtrace:
>
> Call Trace:
> __schedule+0x2d4/0xae0
> schedule+0x3d/0x90
> btrfs_start_ordered_extent+0x160/0x200 [btrfs]
> ? wake_atomic_t_function+0x60/0x60
> btrfs_run_ordered_extent_work+0x25/0x40 [btrfs]
> btrfs_scrubparity_helper+0x1c1/0x620 [btrfs]
> btrfs_flush_delalloc_helper+0xe/0x10 [btrfs]
> process_one_work+0x2af/0x720
> ? process_one_work+0x22b/0x720
> worker_thread+0x4b/0x4f0
> kthread+0x10f/0x150
> ? process_one_work+0x720/0x720
> ? kthread_create_on_node+0x40/0x40
> ret_from_fork+0x2e/0x40
>
> The direct cause is the error handler in run_delalloc_nocow() doesn't
> handle error from btrfs_reloc_clone_csums() well.
>
> The error handler of run_delalloc_nocow() will clear dirty and finish IO
> for the pages in that extent.
> However we have already inserted one ordered extent.
> And that ordered extent is relying on endio hooks to wait all its pages
> to finish, while only the first page will finish.
>
> This makes that ordered extent never finish, so blocking the file
> system.
>
> Although the root cause is still in RAID5/6, it won't hurt to fix the
> error routine first.
>
> This patch will slightly modify one existing function,
> btrfs_endio_direct_write_update_ordered() to handle free space inode,
> just like what btrfs_writepage_end_io_hook() does.
>
> And use it as base to implement one inline function,
> btrfs_cleanup_ordered_extents() to handle the error in
> run_delalloc_nocow() and cow_file_range().
>
> For compression, it's calling writepage_end_io_hook() itself to handle
> its error, and any submitted ordered extent will have its bio submitted,
> so no need to worry about compression part.
>
> Suggested-by: Filipe Manana <[email protected]>
> Signed-off-by: Qu Wenruo <[email protected]>
> ---
> v2:
> Add BTRFS_ORDERED_SKIP_METADATA flag to avoid double reducing
> outstanding extents, which is already done by
> extent_clear_unlock_delalloc()
> ---
> fs/btrfs/inode.c | 75
> +++++++++++++++++++++++++++++++++++++++++--------
> fs/btrfs/ordered-data.h | 2 ++
> 2 files changed, 66 insertions(+), 11 deletions(-)
>
> diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
> index 1e861a063721..a0b09ff73eae 100644
> --- a/fs/btrfs/inode.c
> +++ b/fs/btrfs/inode.c
> @@ -116,6 +116,41 @@ static struct extent_map *create_pinned_em(struct inode
> *inode, u64 start,
>
> static int btrfs_dirty_inode(struct inode *inode);
>
> +static void __endio_write_update_ordered(struct inode *inode,
> + const u64 offset,
> + const u64 bytes,
> + const int uptodate,
> + const int skip_meta);
> +static inline void btrfs_endio_direct_write_update_ordered(struct inode
> *inode,
> + const u64 offset,
> + const u64 bytes,
> + const int uptodate)
> +{
> + return __endio_write_update_ordered(inode, offset, bytes, uptodate, 0);
> +}
> +
> +/*
> + * Set error bit and cleanup all ordered extents in specified range of
> @inode.
> + *
> + * This is for error case where ordered extent(s) is submitted but
> + * corresponding bio is not submitted.
> + * This can make waiter on such ordered extent never finish, as there is no
> + * endio hook called to finish such ordered extent.
> + */
> +static inline void btrfs_cleanup_ordered_extents(struct inode *inode,
> + const u64 offset,
> + const u64 bytes)
> +{
> + /*
> + * In error handler, we have extent_clear_unlock_delalloc() called
> + * to reduce our metadata space reservation and outstanding extents.
> + *
> + * So here, we don't need finish_ordered_io() to free metadata space
> + * for us, or we will underflow outstanding extents.
> + */
> + return __endio_write_update_ordered(inode, offset, bytes, 0, 1);
> +}
> +
> #ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS
> void btrfs_test_inode_set_ops(struct inode *inode)
> {
> @@ -237,7 +272,6 @@ static int insert_inline_extent(struct btrfs_trans_handle
> *trans,
> return err;
> }
>
> -
> /*
> * conditionally insert an inline extent into the file. This
> * does the checks required to make sure the data is small enough
> @@ -1096,6 +1130,7 @@ static noinline int cow_file_range(struct inode *inode,
> EXTENT_DELALLOC | EXTENT_DEFRAG,
> PAGE_UNLOCK | PAGE_CLEAR_DIRTY |
> PAGE_SET_WRITEBACK | PAGE_END_WRITEBACK);
> + btrfs_cleanup_ordered_extents(inode, start, end - start + 1);
Note that @start is rolling forward in the 'while' loop, using start here won't
cleanup previous added ordered extent.
Also, the above extent_clear_unlock_extent() doesn't cover previous added range,
so it won't release metadata, either.
Thanks,
-liubo
> goto out;
> }
>
> @@ -1538,7 +1573,7 @@ static noinline int run_delalloc_nocow(struct inode
> *inode,
> if (!ret)
> ret = err;
>
> - if (ret && cur_offset < end)
> + if (ret && cur_offset < end) {
> extent_clear_unlock_delalloc(inode, cur_offset, end, end,
> locked_page, EXTENT_LOCKED |
> EXTENT_DELALLOC | EXTENT_DEFRAG |
> @@ -1546,6 +1581,8 @@ static noinline int run_delalloc_nocow(struct inode
> *inode,
> PAGE_CLEAR_DIRTY |
> PAGE_SET_WRITEBACK |
> PAGE_END_WRITEBACK);
> + btrfs_cleanup_ordered_extents(inode, start, end - start + 1);
> + }
> btrfs_free_path(path);
> return ret;
> }
> @@ -2889,6 +2926,10 @@ static int btrfs_finish_ordered_io(struct
> btrfs_ordered_extent *ordered_extent)
>
> nolock = btrfs_is_free_space_inode(inode);
>
> + /* Ordered extent with SKIP_META implies IOERR */
> + if (test_bit(BTRFS_ORDERED_SKIP_META, &ordered_extent->flags))
> + ASSERT(test_bit(BTRFS_ORDERED_IOERR, &ordered_extent->flags));
> +
> if (test_bit(BTRFS_ORDERED_IOERR, &ordered_extent->flags)) {
> ret = -EIO;
> goto out;
> @@ -3008,7 +3049,8 @@ static int btrfs_finish_ordered_io(struct
> btrfs_ordered_extent *ordered_extent)
> ordered_extent->file_offset +
> ordered_extent->len - 1, &cached_state, GFP_NOFS);
> out:
> - if (root != fs_info->tree_root)
> + if (root != fs_info->tree_root &&
> + !test_bit(BTRFS_ORDERED_SKIP_META, &ordered_extent->flags))
> btrfs_delalloc_release_metadata(inode, ordered_extent->len);
> if (trans)
> btrfs_end_transaction(trans);
> @@ -8185,17 +8227,28 @@ static void btrfs_endio_direct_read(struct bio *bio)
> bio_put(bio);
> }
>
> -static void btrfs_endio_direct_write_update_ordered(struct inode *inode,
> - const u64 offset,
> - const u64 bytes,
> - const int uptodate)
> +static void __endio_write_update_ordered(struct inode *inode,
> + const u64 offset,
> + const u64 bytes,
> + const int uptodate,
> + const int skip_meta)
> {
> struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
> struct btrfs_ordered_extent *ordered = NULL;
> + struct btrfs_workqueue *wq;
> + btrfs_work_func_t func;
> u64 ordered_offset = offset;
> u64 ordered_bytes = bytes;
> int ret;
>
> + if (btrfs_is_free_space_inode(inode)) {
> + wq = fs_info->endio_freespace_worker;
> + func = btrfs_freespace_write_helper;
> + } else {
> + wq = fs_info->endio_write_workers;
> + func = btrfs_endio_write_helper;
> + }
> +
> again:
> ret = btrfs_dec_test_first_ordered_pending(inode, &ordered,
> &ordered_offset,
> @@ -8203,10 +8256,10 @@ static void
> btrfs_endio_direct_write_update_ordered(struct inode *inode,
> uptodate);
> if (!ret)
> goto out_test;
> -
> - btrfs_init_work(&ordered->work, btrfs_endio_write_helper,
> - finish_ordered_fn, NULL, NULL);
> - btrfs_queue_work(fs_info->endio_write_workers, &ordered->work);
> + if (skip_meta)
> + set_bit(BTRFS_ORDERED_SKIP_META, &ordered->flags);
> + btrfs_init_work(&ordered->work, func, finish_ordered_fn, NULL, NULL);
> + btrfs_queue_work(wq, &ordered->work);
> out_test:
> /*
> * our bio might span multiple ordered extents. If we haven't
> diff --git a/fs/btrfs/ordered-data.h b/fs/btrfs/ordered-data.h
> index 5f2b0ca28705..1434372c6352 100644
> --- a/fs/btrfs/ordered-data.h
> +++ b/fs/btrfs/ordered-data.h
> @@ -75,6 +75,8 @@ struct btrfs_ordered_sum {
> * in the logging code. */
> #define BTRFS_ORDERED_PENDING 11 /* We are waiting for this ordered extent to
> * complete in the current transaction. */
> +#define BTRFS_ORDERED_SKIP_META 12 /* No need to free metadata */
> +
> struct btrfs_ordered_extent {
> /* logical offset in the file */
> u64 file_offset;
> --
> 2.11.1
>
>
>
> --
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