From 4254b0bbb1c0826b7443ffa593576696bc591aa2 Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Mon, 31 Aug 2009 20:57:14 -0300 Subject: [PATCH] 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 Reviewed-by: Alex Elder Signed-off-by: Felix Blyakher --- fs/xfs/xfs_ialloc.c | 291 +++++++++++++++++++++----------------------- 1 file changed, 138 insertions(+), 153 deletions(-) diff --git a/fs/xfs/xfs_ialloc.c b/fs/xfs/xfs_ialloc.c index 18bf6eece54d..7679c1633053 100644 --- a/fs/xfs/xfs_ialloc.c +++ b/fs/xfs/xfs_ialloc.c @@ -589,6 +589,37 @@ nextag: } } +/* + * Try to retrieve the next record to the left/right from the current one. + */ +STATIC int +xfs_ialloc_next_rec( + struct xfs_btree_cur *cur, + xfs_inobt_rec_incore_t *rec, + int *done, + int left) +{ + int error; + int i; + + if (left) + error = xfs_btree_decrement(cur, 0, &i); + else + error = xfs_btree_increment(cur, 0, &i); + + if (error) + return error; + *done = !i; + if (i) { + error = xfs_inobt_get_rec(cur, rec, &i); + if (error) + return error; + XFS_WANT_CORRUPTED_RETURN(i == 1); + } + + return 0; +} + /* * Visible inode allocation functions. @@ -644,8 +675,8 @@ xfs_dialloc( int j; /* result code */ xfs_mount_t *mp; /* file system mount structure */ int offset; /* index of inode in chunk */ - xfs_agino_t pagino; /* parent's a.g. relative inode # */ - xfs_agnumber_t pagno; /* parent's allocation group number */ + xfs_agino_t pagino; /* parent's AG relative inode # */ + xfs_agnumber_t pagno; /* parent's AG number */ xfs_inobt_rec_incore_t rec; /* inode allocation record */ xfs_agnumber_t tagno; /* testing allocation group number */ xfs_btree_cur_t *tcur; /* temp cursor */ @@ -781,186 +812,140 @@ nextag: goto error0; /* - * If in the same a.g. as the parent, try to get near the parent. + * If in the same AG as the parent, try to get near the parent. */ if (pagno == agno) { - if ((error = xfs_inobt_lookup_le(cur, pagino, 0, 0, &i))) + int doneleft; /* done, to the left */ + int doneright; /* done, to the right */ + + error = xfs_inobt_lookup_le(cur, pagino, 0, 0, &i); + if (error) + goto error0; + XFS_WANT_CORRUPTED_GOTO(i == 1, error0); + + error = xfs_inobt_get_rec(cur, &rec, &j); + if (error) goto error0; - if (i != 0 && - (error = xfs_inobt_get_rec(cur, &rec, &j)) == 0 && - j == 1 && - rec.ir_freecount > 0) { + XFS_WANT_CORRUPTED_GOTO(i == 1, error0); + + if (rec.ir_freecount > 0) { /* * Found a free inode in the same chunk - * as parent, done. + * as the parent, done. */ + goto alloc_inode; } + + /* - * In the same a.g. as parent, but parent's chunk is full. + * In the same AG as parent, but parent's chunk is full. */ - else { - int doneleft; /* done, to the left */ - int doneright; /* done, to the right */ - if (error) - goto error0; - ASSERT(i == 1); - ASSERT(j == 1); - /* - * Duplicate the cursor, search left & right - * simultaneously. - */ - if ((error = xfs_btree_dup_cursor(cur, &tcur))) - goto error0; - /* - * Search left with tcur, back up 1 record. - */ - if ((error = xfs_btree_decrement(tcur, 0, &i))) - goto error1; - doneleft = !i; - if (!doneleft) { - error = xfs_inobt_get_rec(tcur, &trec, &i); - if (error) - goto error1; - XFS_WANT_CORRUPTED_GOTO(i == 1, error1); + /* duplicate the cursor, search left & right simultaneously */ + error = xfs_btree_dup_cursor(cur, &tcur); + if (error) + goto error0; + + /* search left with tcur, back up 1 record */ + error = xfs_ialloc_next_rec(tcur, &trec, &doneleft, 1); + if (error) + goto error1; + + /* search right with cur, go forward 1 record. */ + error = xfs_ialloc_next_rec(cur, &rec, &doneright, 0); + if (error) + goto error1; + + /* + * Loop until we find an inode chunk with a free inode. + */ + while (!doneleft || !doneright) { + int useleft; /* using left inode chunk this time */ + + /* figure out the closer block if both are valid. */ + if (!doneleft && !doneright) { + useleft = pagino - + (trec.ir_startino + XFS_INODES_PER_CHUNK - 1) < + rec.ir_startino - pagino; + } else { + useleft = !doneleft; } - /* - * Search right with cur, go forward 1 record. - */ - if ((error = xfs_btree_increment(cur, 0, &i))) - goto error1; - doneright = !i; - if (!doneright) { - error = xfs_inobt_get_rec(cur, &rec, &i); - if (error) - goto error1; - XFS_WANT_CORRUPTED_GOTO(i == 1, error1); + + /* free inodes to the left? */ + if (useleft && trec.ir_freecount) { + rec = trec; + xfs_btree_del_cursor(cur, XFS_BTREE_NOERROR); + cur = tcur; + goto alloc_inode; } - /* - * Loop until we find the closest inode chunk - * with a free one. - */ - while (!doneleft || !doneright) { - int useleft; /* using left inode - chunk this time */ - /* - * Figure out which block is closer, - * if both are valid. - */ - if (!doneleft && !doneright) - useleft = - pagino - - (trec.ir_startino + - XFS_INODES_PER_CHUNK - 1) < - rec.ir_startino - pagino; - else - useleft = !doneleft; - /* - * If checking the left, does it have - * free inodes? - */ - if (useleft && trec.ir_freecount) { - /* - * Yes, set it up as the chunk to use. - */ - rec = trec; - xfs_btree_del_cursor(cur, - XFS_BTREE_NOERROR); - cur = tcur; - break; - } - /* - * If checking the right, does it have - * free inodes? - */ - if (!useleft && rec.ir_freecount) { - /* - * Yes, it's already set up. - */ - xfs_btree_del_cursor(tcur, - XFS_BTREE_NOERROR); - break; - } - /* - * If used the left, get another one - * further left. - */ - if (useleft) { - if ((error = xfs_btree_decrement(tcur, 0, - &i))) - goto error1; - doneleft = !i; - if (!doneleft) { - error = xfs_inobt_get_rec( - tcur, &trec, &i); - if (error) - goto error1; - XFS_WANT_CORRUPTED_GOTO(i == 1, - error1); - } - } - /* - * If used the right, get another one - * further right. - */ - else { - if ((error = xfs_btree_increment(cur, 0, - &i))) - goto error1; - doneright = !i; - if (!doneright) { - error = xfs_inobt_get_rec( - cur, &rec, &i); - if (error) - goto error1; - XFS_WANT_CORRUPTED_GOTO(i == 1, - error1); - } - } + /* free inodes to the right? */ + if (!useleft && rec.ir_freecount) { + xfs_btree_del_cursor(tcur, XFS_BTREE_NOERROR); + goto alloc_inode; } - ASSERT(!doneleft || !doneright); + + /* get next record to check */ + if (useleft) { + error = xfs_ialloc_next_rec(tcur, &trec, + &doneleft, 1); + } else { + error = xfs_ialloc_next_rec(cur, &rec, + &doneright, 0); + } + if (error) + goto error1; } + ASSERT(!doneleft || !doneright); } + /* - * In a different a.g. from the parent. + * In a different AG from the parent. * See if the most recently allocated block has any free. */ else if (be32_to_cpu(agi->agi_newino) != NULLAGINO) { - if ((error = xfs_inobt_lookup_eq(cur, - be32_to_cpu(agi->agi_newino), 0, 0, &i))) + error = xfs_inobt_lookup_eq(cur, be32_to_cpu(agi->agi_newino), + 0, 0, &i); + if (error) goto error0; - if (i == 1 && - (error = xfs_inobt_get_rec(cur, &rec, &j)) == 0 && - j == 1 && - rec.ir_freecount > 0) { - /* - * The last chunk allocated in the group still has - * a free inode. - */ + + if (i == 1) { + error = xfs_inobt_get_rec(cur, &rec, &j); + if (error) + goto error0; + + if (j == 1 && rec.ir_freecount > 0) { + /* + * The last chunk allocated in the group + * still has a free inode. + */ + goto alloc_inode; + } } + /* - * None left in the last group, search the whole a.g. + * None left in the last group, search the whole AG */ - else { + error = xfs_inobt_lookup_ge(cur, 0, 0, 0, &i); + if (error) + goto error0; + XFS_WANT_CORRUPTED_GOTO(i == 1, error0); + + for (;;) { + error = xfs_inobt_get_rec(cur, &rec, &i); if (error) goto error0; - if ((error = xfs_inobt_lookup_ge(cur, 0, 0, 0, &i))) + XFS_WANT_CORRUPTED_GOTO(i == 1, error0); + if (rec.ir_freecount > 0) + break; + error = xfs_btree_increment(cur, 0, &i); + if (error) goto error0; - ASSERT(i == 1); - for (;;) { - error = xfs_inobt_get_rec(cur, &rec, &i); - if (error) - goto error0; - XFS_WANT_CORRUPTED_GOTO(i == 1, error0); - if (rec.ir_freecount > 0) - break; - if ((error = xfs_btree_increment(cur, 0, &i))) - goto error0; - XFS_WANT_CORRUPTED_GOTO(i == 1, error0); - } + XFS_WANT_CORRUPTED_GOTO(i == 1, error0); } } + +alloc_inode: offset = xfs_ialloc_find_free(&rec.ir_free); ASSERT(offset >= 0); ASSERT(offset < XFS_INODES_PER_CHUNK); -- 2.20.1