Commit 0c1d9e4a authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Darrick J. Wong
Browse files

xfs: simplify validation of the unwritten extent bit 



XFS only supports the unwritten extent bit in the data fork, and only if
the file system has a version 5 superblock or the unwritten extent
feature bit.

We currently have two routines that validate the invariant:
xfs_check_nostate_extents which return -EFSCORRUPTED when it's not met,
and xfs_validate_extent that triggers and assert in debug build.

Both of them iterate over all extents of an inode fork when called,
which isn't very efficient.

This patch instead adds a new helper that verifies the invariant one
extent at a time, and calls it from the places where we iterate over
all extents to converted them from or two the in-memory format.  The
callers then return -EFSCORRUPTED when reading invalid extents from
disk, or trigger an assert when writing them to disk.

Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarDarrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: default avatarDarrick J. Wong <darrick.wong@oracle.com>
parent 37f7f9bb

fs/xfs/libxfs/xfs_bmap.c

+2 −14
Original line number Diff line number Diff line
@@ -1231,7 +1231,6 @@ xfs_bmap_read_extents( 
	xfs_fsblock_t		bno;	/* block # of "block" */

	xfs_buf_t		*bp;	/* buffer for "block" */

	int			error;	/* error return value */

	xfs_exntfmt_t		exntf;	/* XFS_EXTFMT_NOSTATE, if checking */

	xfs_extnum_t		i, j;	/* index into the extents list */

	xfs_ifork_t		*ifp;	/* fork structure */

	int			level;	/* btree level, for checking */
@@ -1242,8 +1241,6 @@ xfs_bmap_read_extents( 


	mp = ip->i_mount;

	ifp = XFS_IFORK_PTR(ip, whichfork);

	exntf = (whichfork != XFS_DATA_FORK) ? XFS_EXTFMT_NOSTATE :

					XFS_EXTFMT_INODE(ip);

	block = ifp->if_broot;

	/*

	 * Root level must use BMAP_BROOT_PTR_ADDR macro to get ptr out.
@@ -1311,18 +1308,9 @@ xfs_bmap_read_extents( 
			xfs_bmbt_rec_host_t *trp = xfs_iext_get_ext(ifp, i);

			trp->l0 = be64_to_cpu(frp->l0);

			trp->l1 = be64_to_cpu(frp->l1);

		}

		if (exntf == XFS_EXTFMT_NOSTATE) {

			/*

			 * Check all attribute bmap btree records and

			 * any "older" data bmap btree records for a

			 * set bit in the "extent flag" position.

			 */

			if (unlikely(xfs_check_nostate_extents(ifp,

					start, num_recs))) {

			if (!xfs_bmbt_validate_extent(mp, whichfork, trp)) {

				XFS_ERROR_REPORT("xfs_bmap_read_extents(2)",

						 XFS_ERRLEVEL_LOW,

						 ip->i_mount);

						 XFS_ERRLEVEL_LOW, mp);

				goto error0;

			}

		}

fs/xfs/libxfs/xfs_bmap.h

+0 −2
Original line number Diff line number Diff line
@@ -244,8 +244,6 @@ int xfs_bmap_del_extent_delay(struct xfs_inode *ip, int whichfork, 
		struct xfs_bmbt_irec *del);

void	xfs_bmap_del_extent_cow(struct xfs_inode *ip, xfs_extnum_t *idx,

		struct xfs_bmbt_irec *got, struct xfs_bmbt_irec *del);

int	xfs_check_nostate_extents(struct xfs_ifork *ifp, xfs_extnum_t idx,

		xfs_extnum_t num);

uint	xfs_default_attroffset(struct xfs_inode *ip);

int	xfs_bmap_shift_extents(struct xfs_trans *tp, struct xfs_inode *ip,

		xfs_fileoff_t *next_fsb, xfs_fileoff_t offset_shift_fsb,

fs/xfs/libxfs/xfs_bmap_btree.c

+0 −26
Original line number Diff line number Diff line
@@ -366,32 +366,6 @@ xfs_bmbt_to_bmdr( 
	memcpy(tpp, fpp, sizeof(*fpp) * dmxr);

}



/*

 * Check extent records, which have just been read, for

 * any bit in the extent flag field. ASSERT on debug

 * kernels, as this condition should not occur.

 * Return an error condition (1) if any flags found,

 * otherwise return 0.

 */



int

xfs_check_nostate_extents(

	xfs_ifork_t		*ifp,

	xfs_extnum_t		idx,

	xfs_extnum_t		num)

{

	for (; num > 0; num--, idx++) {

		xfs_bmbt_rec_host_t *ep = xfs_iext_get_ext(ifp, idx);

		if ((ep->l0 >>

		     (64 - BMBT_EXNTFLAG_BITLEN)) != 0) {

			ASSERT(0);

			return 1;

		}

	}

	return 0;

}





STATIC struct xfs_btree_cur *

xfs_bmbt_dup_cursor(

	struct xfs_btree_cur	*cur)

fs/xfs/libxfs/xfs_bmap_btree.h

+14 −7
Original line number Diff line number Diff line
@@ -24,13 +24,6 @@ struct xfs_mount; 
struct xfs_inode;

struct xfs_trans;



/*

 * Extent state and extent format macros.

 */

#define XFS_EXTFMT_INODE(x)	\

	(xfs_sb_version_hasextflgbit(&((x)->i_mount->m_sb)) ? \

		XFS_EXTFMT_HASSTATE : XFS_EXTFMT_NOSTATE)



/*

 * Btree block header size depends on a superblock flag.

 */
@@ -139,4 +132,18 @@ extern int xfs_bmbt_change_owner(struct xfs_trans *tp, struct xfs_inode *ip, 
extern struct xfs_btree_cur *xfs_bmbt_init_cursor(struct xfs_mount *,

		struct xfs_trans *, struct xfs_inode *, int);



/*

 * Check that the extent does not contain an invalid unwritten extent flag.

 */

static inline bool xfs_bmbt_validate_extent(struct xfs_mount *mp, int whichfork,

		struct xfs_bmbt_rec_host *ep)

{

	if (ep->l0 >> (64 - BMBT_EXNTFLAG_BITLEN) == 0)

		return true;

	if (whichfork == XFS_DATA_FORK &&

	    xfs_sb_version_hasextflgbit(&mp->m_sb))

		return true;

	return false;

}



#endif	/* __XFS_BMAP_BTREE_H__ */

fs/xfs/libxfs/xfs_format.h

+0 −8
Original line number Diff line number Diff line
@@ -1575,14 +1575,6 @@ static inline xfs_filblks_t startblockval(xfs_fsblock_t x) 
	return (xfs_filblks_t)((x) & ~STARTBLOCKMASK);

}



/*

 * Possible extent formats.

 */

typedef enum {

	XFS_EXTFMT_NOSTATE = 0,

	XFS_EXTFMT_HASSTATE

} xfs_exntfmt_t;



/*

 * Possible extent states.

 */

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