From: Dave Chinner <dchinner@xxxxxxxxxx>
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: Dave Chinner <dchinner@xxxxxxxxxx>
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
Reviewed-by: Alex Elder <aelder@xxxxxxx>
Index: xfs/fs/xfs/xfs_bmap.c
===================================================================
--- xfs.orig/fs/xfs/xfs_bmap.c 2011-08-23 21:07:51.327604480 +0200
+++ xfs/fs/xfs/xfs_bmap.c 2011-08-23 21:08:45.150646228 +0200
@@ -4249,6 +4249,107 @@ xfs_bmap_validate_ret(
/*
+ * 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.
* Adds blocks to file if a write ("flags & XFS_BMAPI_WRITE" set)
@@ -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
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