Btrfs: fix warning of bytes_may_use

While running generic/019, dmesg got several warnings from
btrfs_free_reserved_data_space().

Test generic/019 produces some disk failures so sumbit dio will get errors,
in which case, btrfs_direct_IO() goes to the error handling and free
bytes_may_use, but the problem is that bytes_may_use has been free'd
during get_block().

This adds a runtime flag to show if we've gone through get_block(), if so,
don't do the cleanup work.

Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Tested-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Chris Mason <clm@fb.com>

diff --git a/fs/btrfs/btrfs_inode.h b/fs/btrfs/btrfs_inode.h
index 0ef5cc1..81220b2 100644 (file)
--- a/fs/btrfs/btrfs_inode.h
+++ b/fs/btrfs/btrfs_inode.h
@@ -44,6 +44,8 @@
 #define BTRFS_INODE_IN_DELALLOC_LIST           9
 #define BTRFS_INODE_READDIO_NEED_LOCK          10
 #define BTRFS_INODE_HAS_PROPS                  11
+/* DIO is ready to submit */
+#define BTRFS_INODE_DIO_READY                  12
 /*
  * The following 3 bits are meant only for the btree inode.
  * When any of them is set, it means an error happened while writing an

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 0b9fb81..b33c0cf 100644 (file)
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -7547,6 +7547,7 @@ unlock:
 
                current->journal_info = outstanding_extents;
                btrfs_free_reserved_data_space(inode, len);
+               set_bit(BTRFS_INODE_DIO_READY, &BTRFS_I(inode)->runtime_flags);
        }
 
        /*
@@ -8357,9 +8358,18 @@ static ssize_t btrfs_direct_IO(struct kiocb *iocb, struct iov_iter *iter,
                                   btrfs_submit_direct, flags);
        if (iov_iter_rw(iter) == WRITE) {
                current->journal_info = NULL;
-               if (ret < 0 && ret != -EIOCBQUEUED)
-                       btrfs_delalloc_release_space(inode, count);
-               else if (ret >= 0 && (size_t)ret < count)
+               if (ret < 0 && ret != -EIOCBQUEUED) {
+                       /*
+                        * If the error comes from submitting stage,
+                        * btrfs_get_blocsk_direct() has free'd data space,
+                        * and metadata space will be handled by
+                        * finish_ordered_fn, don't do that again to make
+                        * sure bytes_may_use is correct.
+                        */
+                       if (!test_and_clear_bit(BTRFS_INODE_DIO_READY,
+                                    &BTRFS_I(inode)->runtime_flags))
+                               btrfs_delalloc_release_space(inode, count);
+               } else if (ret >= 0 && (size_t)ret < count)
                        btrfs_delalloc_release_space(inode,
                                                     count - (size_t)ret);
        }