On Fri, Aug 14, 2020 at 01:38:31PM +0530, Chandan Babu R wrote:
> Moving an extent to data fork can cause a sub-interval of an existing
> extent to be unmapped. This will increase extent count by 1. Mapping in
> the new extent can increase the extent count by 1 again i.e.
> | Old extent | New extent | Old extent |
> Hence number of extents increases by 2.
>
> Signed-off-by: Chandan Babu R <chandanrlinux@xxxxxxxxx>
> ---
> fs/xfs/libxfs/xfs_inode_fork.h | 10 +++++++++-
> fs/xfs/xfs_reflink.c | 6 ++++++
> 2 files changed, 15 insertions(+), 1 deletion(-)
>
> diff --git a/fs/xfs/libxfs/xfs_inode_fork.h b/fs/xfs/libxfs/xfs_inode_fork.h
> index 63f83a13e0a8..d750bdff17c9 100644
> --- a/fs/xfs/libxfs/xfs_inode_fork.h
> +++ b/fs/xfs/libxfs/xfs_inode_fork.h
> @@ -76,7 +76,15 @@ struct xfs_ifork {
> * increase by 1.
> */
> #define XFS_IEXT_INSERT_HOLE_CNT 1
> -
> +/*
> + * Moving an extent to data fork can cause a sub-interval of an
> + * existing extent to be unmapped. This will increase extent count by
> + * 1. Mapping in the new extent can increase the extent count by 1
> + * again i.e.
> + * | Old extent | New extent | Old extent |
This comment is a little oddly formatted, mostly because my brain
thought that the line starting with "1. Mapping" was a numbered bullet
list. If you reflow the comment further outward, you can get it to look
like this:
/*
* Moving an extent to data fork can cause a sub-interval of an existing
* extent to be unmapped, increasing extent count by 1. Mapping in the
* new extent can also increase the extent count by 1:
* | Old extent | New extent | Old extent |
* Hence number of extents increases by 2.
*/
#define XFS_IEXT_REFLINK_END_COW_CNT 2
--D
> + * Hence number of extents increases by 2.
> + */
> +#define XFS_IEXT_REFLINK_END_COW_CNT 2
> /*
> * Fork handling.
> */
> diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c
> index aac83f9d6107..04a7754ee681 100644
> --- a/fs/xfs/xfs_reflink.c
> +++ b/fs/xfs/xfs_reflink.c
> @@ -29,6 +29,7 @@
> #include "xfs_iomap.h"
> #include "xfs_sb.h"
> #include "xfs_ag_resv.h"
> +#include "xfs_trans_resv.h"
>
> /*
> * Copy on Write of Shared Blocks
> @@ -628,6 +629,11 @@ xfs_reflink_end_cow_extent(
> xfs_ilock(ip, XFS_ILOCK_EXCL);
> xfs_trans_ijoin(tp, ip, 0);
>
> + error = xfs_iext_count_may_overflow(ip, XFS_DATA_FORK,
> + XFS_IEXT_REFLINK_END_COW_CNT);
> + if (error)
> + goto out_cancel;
> +
> /*
> * In case of racing, overlapping AIO writes no COW extents might be
> * left by the time I/O completes for the loser of the race. In that
> --
> 2.28.0
>
