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xfs: untangle xfs_dialloc
Clarify the control flow in xfs_dialloc. Factor out a helper to go to the next node from the current one and improve the control flow by expanding composite if statements and using gotos. The xfs_ialloc_next_rec helper is borrowed from Dave Chinners dynamic allocation policy patches. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Alex Elder <aelder@sgi.com> Signed-off-by: Felix Blyakher <felixb@sgi.com>
This commit is contained in:
Christoph Hellwig
Felix Blyakher
parent
0b48db80ba
commit
4254b0bbb1
1 changed files with 143 additions and 158 deletions
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@ -589,6 +589,37 @@ nextag:
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}
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}
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/*
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* Try to retrieve the next record to the left/right from the current one.
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*/
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STATIC int
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xfs_ialloc_next_rec(
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struct xfs_btree_cur *cur,
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xfs_inobt_rec_incore_t *rec,
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int *done,
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int left)
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{
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int error;
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int i;
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if (left)
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error = xfs_btree_decrement(cur, 0, &i);
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else
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error = xfs_btree_increment(cur, 0, &i);
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if (error)
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return error;
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*done = !i;
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if (i) {
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error = xfs_inobt_get_rec(cur, rec, &i);
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if (error)
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return error;
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XFS_WANT_CORRUPTED_RETURN(i == 1);
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}
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return 0;
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}
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/*
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* Visible inode allocation functions.
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@ -644,8 +675,8 @@ xfs_dialloc(
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int j; /* result code */
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xfs_mount_t *mp; /* file system mount structure */
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int offset; /* index of inode in chunk */
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xfs_agino_t pagino; /* parent's a.g. relative inode # */
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xfs_agnumber_t pagno; /* parent's allocation group number */
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xfs_agino_t pagino; /* parent's AG relative inode # */
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xfs_agnumber_t pagno; /* parent's AG number */
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xfs_inobt_rec_incore_t rec; /* inode allocation record */
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xfs_agnumber_t tagno; /* testing allocation group number */
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xfs_btree_cur_t *tcur; /* temp cursor */
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@ -781,186 +812,140 @@ nextag:
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goto error0;
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/*
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* If in the same a.g. as the parent, try to get near the parent.
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* If in the same AG as the parent, try to get near the parent.
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*/
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if (pagno == agno) {
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if ((error = xfs_inobt_lookup_le(cur, pagino, 0, 0, &i)))
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int doneleft; /* done, to the left */
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int doneright; /* done, to the right */
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error = xfs_inobt_lookup_le(cur, pagino, 0, 0, &i);
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if (error)
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goto error0;
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if (i != 0 &&
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(error = xfs_inobt_get_rec(cur, &rec, &j)) == 0 &&
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j == 1 &&
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rec.ir_freecount > 0) {
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XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
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error = xfs_inobt_get_rec(cur, &rec, &j);
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if (error)
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goto error0;
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XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
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if (rec.ir_freecount > 0) {
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/*
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* Found a free inode in the same chunk
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* as parent, done.
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* as the parent, done.
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*/
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goto alloc_inode;
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}
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/*
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* In the same a.g. as parent, but parent's chunk is full.
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* In the same AG as parent, but parent's chunk is full.
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*/
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else {
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int doneleft; /* done, to the left */
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int doneright; /* done, to the right */
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/* duplicate the cursor, search left & right simultaneously */
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error = xfs_btree_dup_cursor(cur, &tcur);
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if (error)
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goto error0;
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/* search left with tcur, back up 1 record */
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error = xfs_ialloc_next_rec(tcur, &trec, &doneleft, 1);
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if (error)
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goto error1;
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/* search right with cur, go forward 1 record. */
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error = xfs_ialloc_next_rec(cur, &rec, &doneright, 0);
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if (error)
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goto error1;
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/*
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* Loop until we find an inode chunk with a free inode.
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*/
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while (!doneleft || !doneright) {
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int useleft; /* using left inode chunk this time */
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/* figure out the closer block if both are valid. */
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if (!doneleft && !doneright) {
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useleft = pagino -
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(trec.ir_startino + XFS_INODES_PER_CHUNK - 1) <
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rec.ir_startino - pagino;
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} else {
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useleft = !doneleft;
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}
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/* free inodes to the left? */
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if (useleft && trec.ir_freecount) {
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rec = trec;
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xfs_btree_del_cursor(cur, XFS_BTREE_NOERROR);
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cur = tcur;
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goto alloc_inode;
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}
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/* free inodes to the right? */
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if (!useleft && rec.ir_freecount) {
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xfs_btree_del_cursor(tcur, XFS_BTREE_NOERROR);
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goto alloc_inode;
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}
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/* get next record to check */
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if (useleft) {
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error = xfs_ialloc_next_rec(tcur, &trec,
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&doneleft, 1);
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} else {
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error = xfs_ialloc_next_rec(cur, &rec,
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&doneright, 0);
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}
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if (error)
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goto error0;
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ASSERT(i == 1);
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ASSERT(j == 1);
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/*
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* Duplicate the cursor, search left & right
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* simultaneously.
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*/
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if ((error = xfs_btree_dup_cursor(cur, &tcur)))
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goto error0;
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/*
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* Search left with tcur, back up 1 record.
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*/
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if ((error = xfs_btree_decrement(tcur, 0, &i)))
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goto error1;
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doneleft = !i;
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if (!doneleft) {
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error = xfs_inobt_get_rec(tcur, &trec, &i);
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if (error)
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goto error1;
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XFS_WANT_CORRUPTED_GOTO(i == 1, error1);
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}
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/*
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* Search right with cur, go forward 1 record.
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*/
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if ((error = xfs_btree_increment(cur, 0, &i)))
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goto error1;
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doneright = !i;
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if (!doneright) {
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error = xfs_inobt_get_rec(cur, &rec, &i);
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if (error)
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goto error1;
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XFS_WANT_CORRUPTED_GOTO(i == 1, error1);
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}
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/*
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* Loop until we find the closest inode chunk
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* with a free one.
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*/
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while (!doneleft || !doneright) {
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int useleft; /* using left inode
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chunk this time */
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/*
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* Figure out which block is closer,
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* if both are valid.
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*/
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if (!doneleft && !doneright)
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useleft =
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pagino -
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(trec.ir_startino +
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XFS_INODES_PER_CHUNK - 1) <
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rec.ir_startino - pagino;
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else
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useleft = !doneleft;
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/*
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* If checking the left, does it have
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* free inodes?
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*/
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if (useleft && trec.ir_freecount) {
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/*
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* Yes, set it up as the chunk to use.
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*/
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rec = trec;
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xfs_btree_del_cursor(cur,
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XFS_BTREE_NOERROR);
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cur = tcur;
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break;
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}
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/*
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* If checking the right, does it have
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* free inodes?
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*/
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if (!useleft && rec.ir_freecount) {
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/*
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* Yes, it's already set up.
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*/
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xfs_btree_del_cursor(tcur,
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XFS_BTREE_NOERROR);
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break;
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}
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/*
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* If used the left, get another one
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* further left.
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*/
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if (useleft) {
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if ((error = xfs_btree_decrement(tcur, 0,
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&i)))
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goto error1;
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doneleft = !i;
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if (!doneleft) {
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error = xfs_inobt_get_rec(
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tcur, &trec, &i);
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if (error)
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goto error1;
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XFS_WANT_CORRUPTED_GOTO(i == 1,
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error1);
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}
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}
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/*
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* If used the right, get another one
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* further right.
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*/
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else {
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if ((error = xfs_btree_increment(cur, 0,
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&i)))
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goto error1;
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doneright = !i;
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if (!doneright) {
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error = xfs_inobt_get_rec(
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cur, &rec, &i);
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if (error)
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goto error1;
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XFS_WANT_CORRUPTED_GOTO(i == 1,
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error1);
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}
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}
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}
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ASSERT(!doneleft || !doneright);
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}
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ASSERT(!doneleft || !doneright);
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}
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/*
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* In a different a.g. from the parent.
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* In a different AG from the parent.
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* See if the most recently allocated block has any free.
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*/
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else if (be32_to_cpu(agi->agi_newino) != NULLAGINO) {
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if ((error = xfs_inobt_lookup_eq(cur,
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be32_to_cpu(agi->agi_newino), 0, 0, &i)))
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error = xfs_inobt_lookup_eq(cur, be32_to_cpu(agi->agi_newino),
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0, 0, &i);
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if (error)
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goto error0;
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if (i == 1 &&
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(error = xfs_inobt_get_rec(cur, &rec, &j)) == 0 &&
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j == 1 &&
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rec.ir_freecount > 0) {
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/*
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* The last chunk allocated in the group still has
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* a free inode.
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*/
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}
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/*
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* None left in the last group, search the whole a.g.
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*/
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else {
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if (i == 1) {
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error = xfs_inobt_get_rec(cur, &rec, &j);
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if (error)
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goto error0;
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if ((error = xfs_inobt_lookup_ge(cur, 0, 0, 0, &i)))
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goto error0;
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ASSERT(i == 1);
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for (;;) {
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error = xfs_inobt_get_rec(cur, &rec, &i);
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if (error)
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goto error0;
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XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
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if (rec.ir_freecount > 0)
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break;
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if ((error = xfs_btree_increment(cur, 0, &i)))
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goto error0;
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XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
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if (j == 1 && rec.ir_freecount > 0) {
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/*
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* The last chunk allocated in the group
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* still has a free inode.
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*/
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goto alloc_inode;
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}
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}
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/*
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* None left in the last group, search the whole AG
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*/
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error = xfs_inobt_lookup_ge(cur, 0, 0, 0, &i);
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if (error)
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goto error0;
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XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
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for (;;) {
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error = xfs_inobt_get_rec(cur, &rec, &i);
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if (error)
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goto error0;
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XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
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if (rec.ir_freecount > 0)
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break;
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error = xfs_btree_increment(cur, 0, &i);
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if (error)
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goto error0;
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XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
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}
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}
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alloc_inode:
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offset = xfs_ialloc_find_free(&rec.ir_free);
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ASSERT(offset >= 0);
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ASSERT(offset < XFS_INODES_PER_CHUNK);
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