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Commit 172ed391 authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Darrick J. Wong
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xfs: don't allocate COW blocks for zeroing holes or unwritten extents 



The iomap zeroing interface is smart enough to skip zeroing holes or
unwritten extents.  Don't subvert this logic for reflink files.

Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarDave Chinner <dchinner@redhat.com>
Reviewed-by: default avatarDarrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: default avatarDarrick J. Wong <darrick.wong@oracle.com>
parent 5b4c845e

fs/xfs/xfs_iomap.c

+10 −1
Original line number Diff line number Diff line
@@ -955,6 +955,13 @@ static inline bool imap_needs_alloc(struct inode *inode, 
		(IS_DAX(inode) && imap->br_state == XFS_EXT_UNWRITTEN);

}



static inline bool needs_cow_for_zeroing(struct xfs_bmbt_irec *imap, int nimaps)

{

	return nimaps &&

		imap->br_startblock != HOLESTARTBLOCK &&

		imap->br_state != XFS_EXT_UNWRITTEN;

}



static inline bool need_excl_ilock(struct xfs_inode *ip, unsigned flags)

{

	/*
@@ -1024,7 +1031,9 @@ xfs_file_iomap_begin( 
			goto out_unlock;

	}



	if ((flags & (IOMAP_WRITE | IOMAP_ZERO)) && xfs_is_reflink_inode(ip)) {

	if (xfs_is_reflink_inode(ip) &&

	    ((flags & IOMAP_WRITE) ||

	     ((flags & IOMAP_ZERO) && needs_cow_for_zeroing(&imap, nimaps)))) {

		if (flags & IOMAP_DIRECT) {

			/*

			 * A reflinked inode will result in CoW alloc.