diff mbox

Btrfs: fix leaking of ordered extents after direct IO write error

Message ID 1449656629-16690-1-git-send-email-fdmanana@kernel.org (mailing list archive)
State Accepted
Headers show

Commit Message

Filipe Manana Dec. 9, 2015, 10:23 a.m. UTC 
From: Filipe Manana <fdmanana@suse.com>

When doing a direct IO write, __blockdev_direct_IO() can call the
btrfs_get_blocks_direct() callback one or more times before it calls the
btrfs_submit_direct() callback. However it can fail after calling the
first callback and before calling the second callback, which is a problem
because the first one creates ordered extents and the second one is the
one that submits bios that cover the ordered extents created by the first
one. That means the ordered extents will never complete nor have any of
the flags BTRFS_ORDERED_IO_DONE / BTRFS_ORDERED_IOERR set, resulting in
subsequent operations (such as other direct IO writes, buffered writes or
hole punching) that lock the same IO range and lookup for ordered extents
in the range to hang forever waiting for those ordered extents because
they can not complete ever, since no bio was submitted.

Fix this by tracking a range of created ordered extents that don't have
yet corresponding bios submitted and completing the ordered extents in
the range if __blockdev_direct_IO() fails with an error.

Signed-off-by: Filipe Manana <fdmanana@suse.com>
---

It applies on top of a patch sent a couple weeks ago with the title:
"Btrfs: fix error path when failing to submit bio for direct IO write"

 fs/btrfs/inode.c | 43 ++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 38 insertions(+), 5 deletions(-)

Comments

kernel test robot Dec. 9, 2015, 10:41 a.m. UTC | #1 
Hi Filipe,

[auto build test ERROR on v4.4-rc4]
[also build test ERROR on next-20151208]
[cannot apply to btrfs/next]

url:    https://github.com/0day-ci/linux/commits/fdmanana-kernel-org/Btrfs-fix-leaking-of-ordered-extents-after-direct-IO-write-error/20151209-182927
config: x86_64-randconfig-x008-12090811 (attached as .config)
reproduce:
        # save the attached .config to linux build tree
        make ARCH=x86_64 

All errors (new ones prefixed by >>):

   fs/btrfs/inode.c: In function 'btrfs_direct_IO':
>> fs/btrfs/inode.c:8528:5: error: implicit declaration of function 'btrfs_endio_direct_write_update_ordered' [-Werror=implicit-function-declaration]
        btrfs_endio_direct_write_update_ordered(inode,
        ^
   cc1: some warnings being treated as errors

vim +/btrfs_endio_direct_write_update_ordered +8528 fs/btrfs/inode.c

  8522				 * without submitting corresponding bios for them, so
  8523				 * cleanup them up to avoid other tasks getting them
  8524				 * and waiting for them to complete forever.
  8525				 */
  8526				if (dio_data.unsubmitted_oe_range_start <
  8527				    dio_data.unsubmitted_oe_range_end)
> 8528					btrfs_endio_direct_write_update_ordered(inode,
  8529						dio_data.unsubmitted_oe_range_start,
  8530						dio_data.unsubmitted_oe_range_end -
  8531						dio_data.unsubmitted_oe_range_start,

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation
Filipe Manana Dec. 9, 2015, 10:46 a.m. UTC | #2 
On Wed, Dec 9, 2015 at 10:41 AM, kbuild test robot <lkp@intel.com> wrote:
> Hi Filipe,
>
> [auto build test ERROR on v4.4-rc4]
> [also build test ERROR on next-20151208]
> [cannot apply to btrfs/next]
>
> url:    https://github.com/0day-ci/linux/commits/fdmanana-kernel-org/Btrfs-fix-leaking-of-ordered-extents-after-direct-IO-write-error/20151209-182927
> config: x86_64-randconfig-x008-12090811 (attached as .config)
> reproduce:
>         # save the attached .config to linux build tree
>         make ARCH=x86_64
>
> All errors (new ones prefixed by >>):
>
>    fs/btrfs/inode.c: In function 'btrfs_direct_IO':
>>> fs/btrfs/inode.c:8528:5: error: implicit declaration of function 'btrfs_endio_direct_write_update_ordered' [-Werror=implicit-function-declaration]
>         btrfs_endio_direct_write_update_ordered(inode,
>         ^
>    cc1: some warnings being treated as errors


Yes test robot. It depends on a previous patch
(https://patchwork.kernel.org/patch/7702051/ /
http://git.kernel.org/cgit/linux/kernel/git/fdmanana/linux.git/commit/?h=integration-4.4&id=cefbb57148831bcdc47f78f5963ff6fb63a29936)
as mentioned in a comment of this patch.

>
> vim +/btrfs_endio_direct_write_update_ordered +8528 fs/btrfs/inode.c
>
>   8522                           * without submitting corresponding bios for them, so
>   8523                           * cleanup them up to avoid other tasks getting them
>   8524                           * and waiting for them to complete forever.
>   8525                           */
>   8526                          if (dio_data.unsubmitted_oe_range_start <
>   8527                              dio_data.unsubmitted_oe_range_end)
>> 8528                                  btrfs_endio_direct_write_update_ordered(inode,
>   8529                                          dio_data.unsubmitted_oe_range_start,
>   8530                                          dio_data.unsubmitted_oe_range_end -
>   8531                                          dio_data.unsubmitted_oe_range_start,
>
> ---
> 0-DAY kernel test infrastructure                Open Source Technology Center
> https://lists.01.org/pipermail/kbuild-all                   Intel Corporation
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diff mbox

Patch

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 269da82..1436799 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -66,6 +66,13 @@  struct btrfs_iget_args {
 	struct btrfs_root *root;
 };
 
+struct btrfs_dio_data {
+	u64 outstanding_extents;
+	u64 reserve;
+	u64 unsubmitted_oe_range_start;
+	u64 unsubmitted_oe_range_end;
+};
+
 static const struct inode_operations btrfs_dir_inode_operations;
 static const struct inode_operations btrfs_symlink_inode_operations;
 static const struct inode_operations btrfs_dir_ro_inode_operations;
@@ -7481,11 +7488,6 @@  static struct extent_map *create_pinned_em(struct inode *inode, u64 start,
 	return em;
 }
 
-struct btrfs_dio_data {
-	u64 outstanding_extents;
-	u64 reserve;
-};
-
 static void adjust_dio_outstanding_extents(struct inode *inode,
 					   struct btrfs_dio_data *dio_data,
 					   const u64 len)
@@ -7669,6 +7671,7 @@  unlock:
 		btrfs_free_reserved_data_space(inode, start, len);
 		WARN_ON(dio_data->reserve < len);
 		dio_data->reserve -= len;
+		dio_data->unsubmitted_oe_range_end = start + len;
 		current->journal_info = dio_data;
 	}
 
@@ -8342,6 +8345,21 @@  static void btrfs_submit_direct(int rw, struct bio *dio_bio,
 		dip->subio_endio = btrfs_subio_endio_read;
 	}
 
+	/*
+	 * Reset the range for unsubmitted ordered extents (to a 0 length range)
+	 * even if we fail to submit a bio, because in such case we do the
+	 * corresponding error handling below and it must not be done a second
+	 * time by btrfs_direct_IO().
+	 */
+	if (write) {
+		struct btrfs_dio_data *dio_data = current->journal_info;
+
+		dio_data->unsubmitted_oe_range_end = dip->logical_offset +
+			dip->bytes;
+		dio_data->unsubmitted_oe_range_start =
+			dio_data->unsubmitted_oe_range_end;
+	}
+
 	ret = btrfs_submit_direct_hook(rw, dip, skip_sum);
 	if (!ret)
 		return;
@@ -8478,6 +8496,8 @@  static ssize_t btrfs_direct_IO(struct kiocb *iocb, struct iov_iter *iter,
 		 * originally calculated.  Abuse current->journal_info for this.
 		 */
 		dio_data.reserve = round_up(count, root->sectorsize);
+		dio_data.unsubmitted_oe_range_start = (u64)offset;
+		dio_data.unsubmitted_oe_range_end = (u64)offset;
 		current->journal_info = &dio_data;
 	} else if (test_bit(BTRFS_INODE_READDIO_NEED_LOCK,
 				     &BTRFS_I(inode)->runtime_flags)) {
@@ -8496,6 +8516,19 @@  static ssize_t btrfs_direct_IO(struct kiocb *iocb, struct iov_iter *iter,
 			if (dio_data.reserve)
 				btrfs_delalloc_release_space(inode, offset,
 							     dio_data.reserve);
+			/*
+			 * On error we might have left some ordered extents
+			 * without submitting corresponding bios for them, so
+			 * cleanup them up to avoid other tasks getting them
+			 * and waiting for them to complete forever.
+			 */
+			if (dio_data.unsubmitted_oe_range_start <
+			    dio_data.unsubmitted_oe_range_end)
+				btrfs_endio_direct_write_update_ordered(inode,
+					dio_data.unsubmitted_oe_range_start,
+					dio_data.unsubmitted_oe_range_end -
+					dio_data.unsubmitted_oe_range_start,
+					0);
 		} else if (ret >= 0 && (size_t)ret < count)
 			btrfs_delalloc_release_space(inode, offset,
 						     count - (size_t)ret);