WRITE and ZERO on a shared extent need to perform COW. For direct io in dax mode, it is handled like WRITE, but with block aligned. So COW seems a bit redundant for it.
Because of COW, new extent has been allocated. The extent list needs to be updated at the end. Signed-off-by: Shiyang Ruan <[email protected]> --- fs/xfs/xfs_iomap.c | 42 +++++++++++++++++++++++++----------------- fs/xfs/xfs_reflink.c | 1 + 2 files changed, 26 insertions(+), 17 deletions(-) diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c index 6116a75f03da..ae3b9bf5d784 100644 --- a/fs/xfs/xfs_iomap.c +++ b/fs/xfs/xfs_iomap.c @@ -930,10 +930,10 @@ xfs_file_iomap_begin( { struct xfs_inode *ip = XFS_I(inode); struct xfs_mount *mp = ip->i_mount; - struct xfs_bmbt_irec imap; + struct xfs_bmbt_irec imap = { 0 }, cmap = { 0 }; xfs_fileoff_t offset_fsb, end_fsb; int nimaps = 1, error = 0; - bool shared = false; + bool shared = false, need_cow = false; unsigned lockmode; if (XFS_FORCED_SHUTDOWN(mp)) @@ -967,6 +967,8 @@ xfs_file_iomap_begin( if (error) goto out_unlock; + cmap = imap; + if (flags & IOMAP_REPORT) { /* Trim the mapping to the nearest shared extent boundary. */ error = xfs_reflink_trim_around_shared(ip, &imap, &shared); @@ -983,8 +985,7 @@ xfs_file_iomap_begin( * been done up front, so we don't need to do them here. */ if (xfs_is_cow_inode(ip)) { - struct xfs_bmbt_irec cmap; - bool directio = (flags & IOMAP_DIRECT); + bool directio = flags & IOMAP_DIRECT; /* if zeroing doesn't need COW allocation, then we are done. */ if ((flags & IOMAP_ZERO) && @@ -992,23 +993,21 @@ xfs_file_iomap_begin( goto out_found; /* may drop and re-acquire the ilock */ - cmap = imap; error = xfs_reflink_allocate_cow(ip, &cmap, &shared, &lockmode, - directio); + directio || IS_DAX(inode)); if (error) goto out_unlock; /* - * For buffered writes we need to report the address of the - * previous block (if there was any) so that the higher level - * write code can perform read-modify-write operations; we - * won't need the CoW fork mapping until writeback. For direct - * I/O, which must be block aligned, we need to report the - * newly allocated address. If the data fork has a hole, copy - * the COW fork mapping to avoid allocating to the data fork. + * WRITE and ZERO on a shared extent under dax mode need to + * perform COW, source address will be reported in srcmap. */ - if (directio || imap.br_startblock == HOLESTARTBLOCK) + if (imap.br_startblock != HOLESTARTBLOCK && IS_DAX(inode) && + shared) { + need_cow = true; + } else { imap = cmap; + } end_fsb = imap.br_startoff + imap.br_blockcount; length = XFS_FSB_TO_B(mp, end_fsb) - offset; @@ -1044,8 +1043,7 @@ xfs_file_iomap_begin( */ if (lockmode == XFS_ILOCK_EXCL) xfs_ilock_demote(ip, lockmode); - error = xfs_iomap_write_direct(ip, offset, length, &imap, - nimaps); + error = xfs_iomap_write_direct(ip, offset, length, &imap, nimaps); if (error) return error; @@ -1053,7 +1051,15 @@ xfs_file_iomap_begin( trace_xfs_iomap_alloc(ip, offset, length, XFS_DATA_FORK, &imap); out_finish: - return xfs_bmbt_to_iomap(ip, iomap, &imap, shared); + if (need_cow) { + error = xfs_bmbt_to_iomap(ip, iomap, &cmap, shared); + if (error) + return error; + iomap->flags |= IOMAP_F_NEW; + iomap->type = IOMAP_COW; + return xfs_bmbt_to_iomap(ip, srcmap, &imap, shared); + } else + return xfs_bmbt_to_iomap(ip, iomap, &imap, shared); out_found: ASSERT(nimaps); @@ -1135,6 +1141,8 @@ xfs_file_iomap_end( if ((flags & IOMAP_WRITE) && iomap->type == IOMAP_DELALLOC) return xfs_file_iomap_end_delalloc(XFS_I(inode), offset, length, written, iomap); + else if (iomap->type == IOMAP_COW && written) + return xfs_reflink_end_cow(XFS_I(inode), offset, length); return 0; } diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c index 68e4257cebb0..a1b000be3699 100644 --- a/fs/xfs/xfs_reflink.c +++ b/fs/xfs/xfs_reflink.c @@ -446,6 +446,7 @@ xfs_reflink_allocate_cow( */ if (!convert_now || imap->br_state == XFS_EXT_NORM) return 0; + imap->br_state = XFS_EXT_NORM; trace_xfs_reflink_convert_cow(ip, imap); return xfs_reflink_convert_cow_locked(ip, offset_fsb, count_fsb); -- 2.17.0
