From ef4736678fc3ea426968bc82f907798ed5f51e85 Mon Sep 17 00:00:00 2001 From: "Darrick J. Wong" Date: Mon, 3 Oct 2016 09:11:34 -0700 Subject: xfs: allocate delayed extents in CoW fork Modify the writepage handler to find and convert pending delalloc extents to real allocations. Furthermore, when we're doing non-cow writes to a part of a file that already has a CoW reservation (the cowextsz hint that we set up in a subsequent patch facilitates this), promote the write to copy-on-write so that the entire extent can get written out as a single extent on disk, thereby reducing post-CoW fragmentation. Christoph moved the CoW support code in _map_blocks to a separate helper function, refactored other functions, and reduced the number of CoW fork lookups, so I merged those changes here to reduce churn. Signed-off-by: Darrick J. Wong Signed-off-by: Christoph Hellwig --- fs/xfs/xfs_reflink.c | 84 ++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 84 insertions(+) (limited to 'fs/xfs/xfs_reflink.c') diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c index 5d796b7f23d7..d953df3a201c 100644 --- a/fs/xfs/xfs_reflink.c +++ b/fs/xfs/xfs_reflink.c @@ -328,3 +328,87 @@ xfs_reflink_reserve_cow_range( return error; } + +/* + * Find the CoW reservation (and whether or not it needs block allocation) + * for a given byte offset of a file. + */ +bool +xfs_reflink_find_cow_mapping( + struct xfs_inode *ip, + xfs_off_t offset, + struct xfs_bmbt_irec *imap, + bool *need_alloc) +{ + struct xfs_bmbt_irec irec; + struct xfs_ifork *ifp; + struct xfs_bmbt_rec_host *gotp; + xfs_fileoff_t bno; + xfs_extnum_t idx; + + ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL | XFS_ILOCK_SHARED)); + ASSERT(xfs_is_reflink_inode(ip)); + + /* Find the extent in the CoW fork. */ + ifp = XFS_IFORK_PTR(ip, XFS_COW_FORK); + bno = XFS_B_TO_FSBT(ip->i_mount, offset); + gotp = xfs_iext_bno_to_ext(ifp, bno, &idx); + if (!gotp) + return false; + + xfs_bmbt_get_all(gotp, &irec); + if (bno >= irec.br_startoff + irec.br_blockcount || + bno < irec.br_startoff) + return false; + + trace_xfs_reflink_find_cow_mapping(ip, offset, 1, XFS_IO_OVERWRITE, + &irec); + + /* If it's still delalloc, we must allocate later. */ + *imap = irec; + *need_alloc = !!(isnullstartblock(irec.br_startblock)); + + return true; +} + +/* + * Trim an extent to end at the next CoW reservation past offset_fsb. + */ +int +xfs_reflink_trim_irec_to_next_cow( + struct xfs_inode *ip, + xfs_fileoff_t offset_fsb, + struct xfs_bmbt_irec *imap) +{ + struct xfs_bmbt_irec irec; + struct xfs_ifork *ifp; + struct xfs_bmbt_rec_host *gotp; + xfs_extnum_t idx; + + if (!xfs_is_reflink_inode(ip)) + return 0; + + /* Find the extent in the CoW fork. */ + ifp = XFS_IFORK_PTR(ip, XFS_COW_FORK); + gotp = xfs_iext_bno_to_ext(ifp, offset_fsb, &idx); + if (!gotp) + return 0; + xfs_bmbt_get_all(gotp, &irec); + + /* This is the extent before; try sliding up one. */ + if (irec.br_startoff < offset_fsb) { + idx++; + if (idx >= ifp->if_bytes / sizeof(xfs_bmbt_rec_t)) + return 0; + gotp = xfs_iext_get_ext(ifp, idx); + xfs_bmbt_get_all(gotp, &irec); + } + + if (irec.br_startoff >= imap->br_startoff + imap->br_blockcount) + return 0; + + imap->br_blockcount = irec.br_startoff - imap->br_startoff; + trace_xfs_reflink_trim_irec(ip, imap); + + return 0; +} -- cgit v1.2.3