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Commit e40c145c authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Greg Kroah-Hartman
Browse files

xfs: xfs_trans_alloc_empty 



This is a partial cherry-pick of commit e89c041338
("xfs: implement the GETFSMAP ioctl"), which also adds this helper, and
a great example of why feature patches should be properly split into
their parts.

Signed-off-by: default avatarDarrick J. Wong <darrick.wong@oracle.com>
[hch: split from the larger patch for -stable]
Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
parent 0e542792

fs/xfs/xfs_trans.c

+22 −0
Original line number Diff line number Diff line
@@ -262,6 +262,28 @@ xfs_trans_alloc( 
	return 0;

}



/*

 * Create an empty transaction with no reservation.  This is a defensive

 * mechanism for routines that query metadata without actually modifying

 * them -- if the metadata being queried is somehow cross-linked (think a

 * btree block pointer that points higher in the tree), we risk deadlock.

 * However, blocks grabbed as part of a transaction can be re-grabbed.

 * The verifiers will notice the corrupt block and the operation will fail

 * back to userspace without deadlocking.

 *

 * Note the zero-length reservation; this transaction MUST be cancelled

 * without any dirty data.

 */

int

xfs_trans_alloc_empty(

	struct xfs_mount		*mp,

	struct xfs_trans		**tpp)

{

	struct xfs_trans_res		resv = {0};



	return xfs_trans_alloc(mp, &resv, 0, 0, XFS_TRANS_NO_WRITECOUNT, tpp);

}



/*

 * Record the indicated change to the given field for application

 * to the file system's superblock when the transaction commits.

fs/xfs/xfs_trans.h

+2 −0
Original line number Diff line number Diff line
@@ -159,6 +159,8 @@ typedef struct xfs_trans { 
int		xfs_trans_alloc(struct xfs_mount *mp, struct xfs_trans_res *resp,

			uint blocks, uint rtextents, uint flags,

			struct xfs_trans **tpp);

int		xfs_trans_alloc_empty(struct xfs_mount *mp,

			struct xfs_trans **tpp);

void		xfs_trans_mod_sb(xfs_trans_t *, uint, int64_t);



struct xfs_buf	*xfs_trans_get_buf_map(struct xfs_trans *tp,