xfs: allow null firstblock in xfs_bmapi_write() when tp is null (3ae2d891) · Commits · 戴 / test

xfs_bmapi_write() always expects a valid firstblock pointer. It immediately dereferences the pointer to help determine how to initialize the bma.minleft field. The remaining accesses are related to modifying btree format forks, which is only relevant for !COW fork callers. The reflink code passes a NULL transaction to xfs_bmapi_write() in a couple places that do COW fork unwritten conversion. The purpose of the firstblock field is to track the first block allocation in the current transaction, so technically firstblock should not be required for these callers either. Tweak xfs_bmapi_write() to initialize the bma correctly without accessing the firstblock pointer if no transaction is provided in the first place. Update the reflink callers to pass NULL instead of otherwise unused firstblock references. Signed-off-by:

Brian Foster <bfoster@redhat.com> Reviewed-by:

Christoph Hellwig <hch@lst.de> Reviewed-by:

Darrick J. Wong <darrick.wong@oracle.com> Signed-off-by:

Darrick J. Wong <darrick.wong@oracle.com>

fs/xfs/libxfs/xfs_bmap.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -4302,7 +4302,7 @@ xfs_bmapi_write(

		XFS_STATS_INC(mp, xs_blk_mapw);

		if (*firstblock == NULLFSBLOCK) {
		if (!tp \|\| *firstblock == NULLFSBLOCK) {
		if (XFS_IFORK_FORMAT(ip, whichfork) == XFS_DINODE_FMT_BTREE)
		bma.minleft = be16_to_cpu(ifp->if_broot->bb_level) + 1;
		else

fs/xfs/xfs_reflink.c

+3 −6

Original line number	Diff line number	Diff line
		@@ -314,7 +314,6 @@ xfs_reflink_convert_cow_extent(
		xfs_fileoff_t offset_fsb,
		xfs_filblks_t count_fsb)
		{
		xfs_fsblock_t first_block = NULLFSBLOCK;
		int nimaps = 1;

		if (imap->br_state == XFS_EXT_NORM)
		@@ -325,8 +324,8 @@ xfs_reflink_convert_cow_extent(
		if (imap->br_blockcount == 0)
		return 0;
		return xfs_bmapi_write(NULL, ip, imap->br_startoff, imap->br_blockcount,
		XFS_BMAPI_COWFORK \| XFS_BMAPI_CONVERT, &first_block,
		0, imap, &nimaps);
		XFS_BMAPI_COWFORK \| XFS_BMAPI_CONVERT, NULL, 0, imap,
		&nimaps);
		}

		/* Convert all of the unwritten CoW extents in a file's range to real ones. */
		@@ -341,7 +340,6 @@ xfs_reflink_convert_cow(
		xfs_fileoff_t end_fsb = XFS_B_TO_FSB(mp, offset + count);
		xfs_filblks_t count_fsb = end_fsb - offset_fsb;
		struct xfs_bmbt_irec imap;
		xfs_fsblock_t first_block = NULLFSBLOCK;
		int nimaps = 1, error = 0;

		ASSERT(count != 0);
		@@ -349,8 +347,7 @@ xfs_reflink_convert_cow(
		xfs_ilock(ip, XFS_ILOCK_EXCL);
		error = xfs_bmapi_write(NULL, ip, offset_fsb, count_fsb,
		XFS_BMAPI_COWFORK \| XFS_BMAPI_CONVERT \|
		XFS_BMAPI_CONVERT_ONLY, &first_block, 0, &imap,
		&nimaps);
		XFS_BMAPI_CONVERT_ONLY, NULL, 0, &imap, &nimaps);
		xfs_iunlock(ip, XFS_ILOCK_EXCL);
		return error;
		}

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