Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 8867bc9b authored by Mandy Kirkconnell's avatar Mandy Kirkconnell Committed by Nathan Scott
Browse files

[XFS] There are a few problems with the new 


xfs_bmap_search_multi_extents() wrapper function that I introduced in mod
xfs-linux:xfs-kern:207393a. The function was added as a wrapper around
xfs_bmap_do_search_extents() to avoid breaking the top-of-tree CXFS
interface.  The idea of the function was basically to extract the target
extent buffer (if muli- level extent allocation mode), then call
xfs_bmap_do_search_extents() with either a pointer to the first extent in
the target buffer or a pointer to the first extent in the file, depending
on which extent mode was being used.  However, in addition to locating the
target extent record for block bno, xfs_bmap_do_search_extents() also sets
four parameters needed by the caller: *lastx, *eofp, *gotp, *prevp. 
Passing only the target extent buffer to xfs_bmap_do_search_extents()
causes *eofp to be set incorrectly if the extent is at the end of the
target list but there are actually more extents in the next er_extbuf.
Likewise, if the extent is the first one in the buffer but NOT the first
in the file, *prevp is incorrectly set to NULL.  Adding the needed
functionality to xfs_bmap_search_multi_extents() to re-set any incorrectly
set fields is redundant and makes the call to xfs_bmap_do_search_extents()
not make much sense when multi-level extent allocation mode is being used.
 This mod basically extracts the two functional components from
xfs_bmap_do_search_extents(), with the intent of obsoleting/removing
xfs_bmap_do_search_extents() after the CXFS mult-level in-core extent
changes are checked in.  The two components are:  1) The binary search to
locate the target extent record, and 2) Setting the four parameters needed
by the caller (*lastx, *eofp, *gotp, *prevp).  Component 1: I created a
new function in xfs_inode.c called xfs_iext_bno_to_ext(), which executes
the binary search to find the target extent record.
xfs_bmap_search_multi_extents() has been modified to call
xfs_iext_bno_to_ext() rather than xfs_bmap_do_search_extents().  Component
2: The parameter setting functionality has been added to
xfs_bmap_search_multi_extents(), eliminating the need for
xfs_bmap_do_search_extents().  These changes make the removal of
xfs_bmap_do_search_extents() trival once the CXFS changes are in place. 
They also allow us to maintain the current XFS interface, using the new
search function introduced in mod xfs-linux:xfs-kern:207393a.

SGI-PV: 928864
SGI-Modid: xfs-linux-melb:xfs-kern:207866a

Signed-off-by: default avatarMandy Kirkconnell <alkirkco@sgi.com>
Signed-off-by: default avatarNathan Scott <nathans@sgi.com>
parent 524fbf5d

fs/xfs/xfs_bmap.c

+30 −27
Original line number Diff line number Diff line
@@ -3575,10 +3575,11 @@ xfs_bmap_do_search_extents( 
}



/*

 * Call xfs_bmap_do_search_extents() to search for the extent

 * record containing block bno. If in multi-level in-core extent

 * allocation mode, find and extract the target extent buffer,

 * otherwise just use the direct extent list.

 * Search the extent records for the entry containing block bno.

 * If bno lies in a hole, point to the next entry.  If bno lies

 * past eof, *eofp will be set, and *prevp will contain the last

 * entry (null if none).  Else, *lastxp will be set to the index

 * of the found entry; *gotp will contain the entry.

 */

xfs_bmbt_rec_t *			/* pointer to found extent entry */

xfs_bmap_search_multi_extents(
@@ -3589,36 +3590,38 @@ xfs_bmap_search_multi_extents( 
	xfs_bmbt_irec_t	*gotp,		/* out: extent entry found */

	xfs_bmbt_irec_t	*prevp)		/* out: previous extent entry found */

{

	xfs_bmbt_rec_t	*base;		/* base of extent records */

	xfs_bmbt_rec_t	*ep;		/* extent record pointer */

	xfs_ext_irec_t	*erp = NULL;	/* indirection array pointer */

	xfs_extnum_t	lastx;		/* last extent index */

	xfs_extnum_t	nextents;	/* number of file extents */



	/*

	 * For multi-level extent allocation mode, find the

	 * target extent list and pass only the contiguous

	 * list to xfs_bmap_do_search_extents. Convert lastx

	 * from a file extent index to an index within the

	 * target extent list.

	 * Initialize the extent entry structure to catch access to

	 * uninitialized br_startblock field.

	 */

	if (ifp->if_flags & XFS_IFEXTIREC) {

		int	erp_idx = 0;

		erp = xfs_iext_bno_to_irec(ifp, bno, &erp_idx);

		base = erp->er_extbuf;

		nextents = erp->er_extcount;

		lastx = ifp->if_lastex - erp->er_extoff;

	gotp->br_startoff = 0xffa5a5a5a5a5a5a5LL;

	gotp->br_blockcount = 0xa55a5a5a5a5a5a5aLL;

	gotp->br_state = XFS_EXT_INVALID;

#if XFS_BIG_BLKNOS

	gotp->br_startblock = 0xffffa5a5a5a5a5a5LL;

#else

	gotp->br_startblock = 0xffffa5a5;

#endif

	prevp->br_startoff = NULLFILEOFF;



	ep = xfs_iext_bno_to_ext(ifp, bno, &lastx);

	if (lastx > 0) {

		xfs_bmbt_get_all(xfs_iext_get_ext(ifp, lastx - 1), prevp);

	}

	if (lastx < (ifp->if_bytes / (uint)sizeof(xfs_bmbt_rec_t))) {

		xfs_bmbt_get_all(ep, gotp);

		*eofp = 0;

	} else {

		base = &ifp->if_u1.if_extents[0];

		nextents = ifp->if_bytes / (uint)sizeof(xfs_bmbt_rec_t);

		lastx = ifp->if_lastex;

		if (lastx > 0) {

			*gotp = *prevp;

		}

	ep = xfs_bmap_do_search_extents(base, lastx, nextents, bno,

					eofp, lastxp, gotp, prevp);

	/* Convert lastx back to file-based index */

	if (ifp->if_flags & XFS_IFEXTIREC) {

		*lastxp += erp->er_extoff;

		*eofp = 1;

		ep = NULL;

	}

	*lastxp = lastx;

	return ep;

}

fs/xfs/xfs_inode.c

+71 −2
Original line number Diff line number Diff line
@@ -4265,12 +4265,81 @@ xfs_iext_destroy( 
	ifp->if_bytes = 0;

}



/*

 * Return a pointer to the extent record for file system block bno.

 */

xfs_bmbt_rec_t *			/* pointer to found extent record */

xfs_iext_bno_to_ext(

	xfs_ifork_t	*ifp,		/* inode fork pointer */

	xfs_fileoff_t	bno,		/* block number to search for */

	xfs_extnum_t	*idxp)		/* index of target extent */

{

	xfs_bmbt_rec_t	*base;		/* pointer to first extent */

	xfs_filblks_t	blockcount = 0;	/* number of blocks in extent */

	xfs_bmbt_rec_t	*ep = NULL;	/* pointer to target extent */

	xfs_ext_irec_t	*erp = NULL;	/* indirection array pointer */

	int		high;		/* upper boundry in search */

	xfs_extnum_t	idx = 0;	/* index of target extent */

	int		low;		/* lower boundry in search */

	xfs_extnum_t	nextents;	/* number of file extents */

	xfs_fileoff_t	startoff = 0;	/* start offset of extent */



	nextents = ifp->if_bytes / (uint)sizeof(xfs_bmbt_rec_t);

	if (nextents == 0) {

		*idxp = 0;

		return NULL;

	}

	low = 0;

	if (ifp->if_flags & XFS_IFEXTIREC) {

		/* Find target extent list */

		int	erp_idx = 0;

		erp = xfs_iext_bno_to_irec(ifp, bno, &erp_idx);

		base = erp->er_extbuf;

		high = erp->er_extcount - 1;

	} else {

		base = ifp->if_u1.if_extents;

		high = nextents - 1;

	}

	/* Binary search extent records */

	while (low <= high) {

		idx = (low + high) >> 1;

		ep = base + idx;

		startoff = xfs_bmbt_get_startoff(ep);

		blockcount = xfs_bmbt_get_blockcount(ep);

		if (bno < startoff) {

			high = idx - 1;

		} else if (bno >= startoff + blockcount) {

			low = idx + 1;

		} else {

			/* Convert back to file-based extent index */

			if (ifp->if_flags & XFS_IFEXTIREC) {

				idx += erp->er_extoff;

			}

			*idxp = idx;

			return ep;

		}

	}

	/* Convert back to file-based extent index */

	if (ifp->if_flags & XFS_IFEXTIREC) {

		idx += erp->er_extoff;

	}

	if (bno >= startoff + blockcount) {

		if (++idx == nextents) {

			ep = NULL;

		} else {

			ep = xfs_iext_get_ext(ifp, idx);

		}

	}

	*idxp = idx;

	return ep;

}



/*

 * Return a pointer to the indirection array entry containing the

 * extent record for filesystem block bno. Store the index of the

 * target irec in *erp_idxp.

 */

xfs_ext_irec_t *

xfs_ext_irec_t *			/* pointer to found extent record */

xfs_iext_bno_to_irec(

	xfs_ifork_t	*ifp,		/* inode fork pointer */

	xfs_fileoff_t	bno,		/* block number to search for */
@@ -4278,7 +4347,7 @@ xfs_iext_bno_to_irec( 
{

	xfs_ext_irec_t	*erp = NULL;	/* indirection array pointer */

	xfs_ext_irec_t	*erp_next;	/* next indirection array entry */

	xfs_extnum_t	erp_idx;	/* indirection array index */

	int		erp_idx;	/* indirection array index */

	int		nlists;		/* number of extent irec's (lists) */

	int		high;		/* binary search upper limit */

	int		low;		/* binary search lower limit */

fs/xfs/xfs_inode.h

+1 −0
Original line number Diff line number Diff line
@@ -478,6 +478,7 @@ void xfs_iext_indirect_to_direct(xfs_ifork_t *); 
void		xfs_iext_direct_to_inline(xfs_ifork_t *, xfs_extnum_t);

void		xfs_iext_inline_to_direct(xfs_ifork_t *, int);

void		xfs_iext_destroy(xfs_ifork_t *);

xfs_bmbt_rec_t	*xfs_iext_bno_to_ext(xfs_ifork_t *, xfs_fileoff_t, int *);

xfs_ext_irec_t	*xfs_iext_bno_to_irec(xfs_ifork_t *, xfs_fileoff_t, int *);

xfs_ext_irec_t	*xfs_iext_idx_to_irec(xfs_ifork_t *, xfs_extnum_t *, int *, int);

void		xfs_iext_irec_init(xfs_ifork_t *);