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Commit aef9a895 authored by Dave Chinner's avatar Dave Chinner Committed by Alex Elder
Browse files

xfs: factor extent map manipulations out of xfs_bmapi 



To further improve the readability of xfs_bmapi(), factor the pure
extent map manipulations out into separate functions. This removes
large blocks of logic from the xfs_bmapi() code loop and makes it
easier to see the operational logic flow for xfs_bmapi().
    
Signed-off-by: default avatarDave Chinner <dchinner@redhat.com>
Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarAlex Elder <aelder@sgi.com>
parent ecee76ba

fs/xfs/xfs_bmap.c

+107 −74
Original line number Diff line number Diff line
@@ -4248,6 +4248,107 @@ xfs_bmap_validate_ret( 
#endif /* DEBUG */





/*

 * Trim the returned map to the required bounds

 */

STATIC void

xfs_bmapi_trim_map(

	struct xfs_bmbt_irec	*mval,

	struct xfs_bmbt_irec	*got,

	xfs_fileoff_t		*bno,

	xfs_filblks_t		len,

	xfs_fileoff_t		obno,

	xfs_fileoff_t		end,

	int			n,

	int			flags)

{

	if ((flags & XFS_BMAPI_ENTIRE) ||

	    got->br_startoff + got->br_blockcount <= obno) {

		*mval = *got;

		if (isnullstartblock(got->br_startblock))

			mval->br_startblock = DELAYSTARTBLOCK;

		return;

	}



	if (obno > *bno)

		*bno = obno;

	ASSERT((*bno >= obno) || (n == 0));

	ASSERT(*bno < end);

	mval->br_startoff = *bno;

	if (isnullstartblock(got->br_startblock))

		mval->br_startblock = DELAYSTARTBLOCK;

	else

		mval->br_startblock = got->br_startblock +

					(*bno - got->br_startoff);

	/*

	 * Return the minimum of what we got and what we asked for for

	 * the length.  We can use the len variable here because it is

	 * modified below and we could have been there before coming

	 * here if the first part of the allocation didn't overlap what

	 * was asked for.

	 */

	mval->br_blockcount = XFS_FILBLKS_MIN(end - *bno,

			got->br_blockcount - (*bno - got->br_startoff));

	mval->br_state = got->br_state;

	ASSERT(mval->br_blockcount <= len);

	return;

}



/*

 * Update and validate the extent map to return

 */

STATIC void

xfs_bmapi_update_map(

	struct xfs_bmbt_irec	**map,

	xfs_fileoff_t		*bno,

	xfs_filblks_t		*len,

	xfs_fileoff_t		obno,

	xfs_fileoff_t		end,

	int			*n,

	int			flags)

{

	xfs_bmbt_irec_t	*mval = *map;



	ASSERT((flags & XFS_BMAPI_ENTIRE) ||

	       ((mval->br_startoff + mval->br_blockcount) <= end));

	ASSERT((flags & XFS_BMAPI_ENTIRE) || (mval->br_blockcount <= *len) ||

	       (mval->br_startoff < obno));



	*bno = mval->br_startoff + mval->br_blockcount;

	*len = end - *bno;

	if (*n > 0 && mval->br_startoff == mval[-1].br_startoff) {

		/* update previous map with new information */

		ASSERT(mval->br_startblock == mval[-1].br_startblock);

		ASSERT(mval->br_blockcount > mval[-1].br_blockcount);

		ASSERT(mval->br_state == mval[-1].br_state);

		mval[-1].br_blockcount = mval->br_blockcount;

		mval[-1].br_state = mval->br_state;

	} else if (*n > 0 && mval->br_startblock != DELAYSTARTBLOCK &&

		   mval[-1].br_startblock != DELAYSTARTBLOCK &&

		   mval[-1].br_startblock != HOLESTARTBLOCK &&

		   mval->br_startblock == mval[-1].br_startblock +

					  mval[-1].br_blockcount &&

		   ((flags & XFS_BMAPI_IGSTATE) ||

			mval[-1].br_state == mval->br_state)) {

		ASSERT(mval->br_startoff ==

		       mval[-1].br_startoff + mval[-1].br_blockcount);

		mval[-1].br_blockcount += mval->br_blockcount;

	} else if (*n > 0 &&

		   mval->br_startblock == DELAYSTARTBLOCK &&

		   mval[-1].br_startblock == DELAYSTARTBLOCK &&

		   mval->br_startoff ==

		   mval[-1].br_startoff + mval[-1].br_blockcount) {

		mval[-1].br_blockcount += mval->br_blockcount;

		mval[-1].br_state = mval->br_state;

	} else if (!((*n == 0) &&

		     ((mval->br_startoff + mval->br_blockcount) <=

		      obno))) {

		mval++;

		(*n)++;

	}

	*map = mval;

}



/*

 * Map file blocks to filesystem blocks.

 * File range is given by the bno/len pair.
@@ -4650,44 +4751,9 @@ xfs_bmapi( 
			n++;

			continue;

		}

		/*

		 * Then deal with the allocated space we found.

		 */

		ASSERT(ep != NULL);

		if (!(flags & XFS_BMAPI_ENTIRE) &&

		    (got.br_startoff + got.br_blockcount > obno)) {

			if (obno > bno)

				bno = obno;

			ASSERT((bno >= obno) || (n == 0));

			ASSERT(bno < end);

			mval->br_startoff = bno;

			if (isnullstartblock(got.br_startblock)) {

				ASSERT(!wr || (flags & XFS_BMAPI_DELAY));

				mval->br_startblock = DELAYSTARTBLOCK;

			} else

				mval->br_startblock =

					got.br_startblock +

					(bno - got.br_startoff);

			/*

			 * Return the minimum of what we got and what we

			 * asked for for the length.  We can use the len

			 * variable here because it is modified below

			 * and we could have been there before coming

			 * here if the first part of the allocation

			 * didn't overlap what was asked for.

			 */

			mval->br_blockcount =

				XFS_FILBLKS_MIN(end - bno, got.br_blockcount -

					(bno - got.br_startoff));

			mval->br_state = got.br_state;

			ASSERT(mval->br_blockcount <= len);

		} else {

			*mval = got;

			if (isnullstartblock(mval->br_startblock)) {

				ASSERT(!wr || (flags & XFS_BMAPI_DELAY));

				mval->br_startblock = DELAYSTARTBLOCK;

			}

		}



		/* Deal with the allocated space we found.  */

		xfs_bmapi_trim_map(mval, &got, &bno, len, obno, end, n, flags);



		/*

		 * Check if writing previously allocated but
@@ -4730,42 +4796,9 @@ xfs_bmapi( 
				continue;

		}



		ASSERT((flags & XFS_BMAPI_ENTIRE) ||

		       ((mval->br_startoff + mval->br_blockcount) <= end));

		ASSERT((flags & XFS_BMAPI_ENTIRE) ||

		       (mval->br_blockcount <= len) ||

		       (mval->br_startoff < obno));

		bno = mval->br_startoff + mval->br_blockcount;

		len = end - bno;

		if (n > 0 && mval->br_startoff == mval[-1].br_startoff) {

			ASSERT(mval->br_startblock == mval[-1].br_startblock);

			ASSERT(mval->br_blockcount > mval[-1].br_blockcount);

			ASSERT(mval->br_state == mval[-1].br_state);

			mval[-1].br_blockcount = mval->br_blockcount;

			mval[-1].br_state = mval->br_state;

		} else if (n > 0 && mval->br_startblock != DELAYSTARTBLOCK &&

			   mval[-1].br_startblock != DELAYSTARTBLOCK &&

			   mval[-1].br_startblock != HOLESTARTBLOCK &&

			   mval->br_startblock ==

			   mval[-1].br_startblock + mval[-1].br_blockcount &&

			   ((flags & XFS_BMAPI_IGSTATE) ||

				mval[-1].br_state == mval->br_state)) {

			ASSERT(mval->br_startoff ==

			       mval[-1].br_startoff + mval[-1].br_blockcount);

			mval[-1].br_blockcount += mval->br_blockcount;

		} else if (n > 0 &&

			   mval->br_startblock == DELAYSTARTBLOCK &&

			   mval[-1].br_startblock == DELAYSTARTBLOCK &&

			   mval->br_startoff ==

			   mval[-1].br_startoff + mval[-1].br_blockcount) {

			mval[-1].br_blockcount += mval->br_blockcount;

			mval[-1].br_state = mval->br_state;

		} else if (!((n == 0) &&

			     ((mval->br_startoff + mval->br_blockcount) <=

			      obno))) {

			mval++;

			n++;

		}

		/* update the extent map to return */

		xfs_bmapi_update_map(&mval, &bno, &len, obno, end, &n, flags);



		/*

		 * If we're done, stop now.  Stop when we've allocated

		 * XFS_BMAP_MAX_NMAP extents no matter what.  Otherwise