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xfs: refactor near mode alloc bnobt scan into separate function

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In preparation to enhance the near mode allocation bnobt scan algorithm, lift
it into a separate function. No functional changes.

Signed-off-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
This commit is contained in:
Brian Foster 2019-10-13 17:10:35 -07:00 committed by Darrick J. Wong
parent 78d7aabdee
commit 0e26d5ca4a
1 changed files with 74 additions and 54 deletions
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128
fs/xfs/libxfs/xfs_alloc.c
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@ -1230,6 +1230,78 @@ xfs_alloc_walk_iter(
return 0;
}
/*
* Search in the by-bno btree to the left and to the right simultaneously until
* in each case we find a large enough free extent or run into the edge of the
* tree. When we run into the edge of the tree, we deactivate that cursor.
*/
STATIC int
xfs_alloc_ag_vextent_bnobt(
struct xfs_alloc_arg *args,
struct xfs_alloc_cur *acur,
int *stat)
{
struct xfs_btree_cur *fbcur = NULL;
int error;
int i;
bool fbinc;
ASSERT(acur->len == 0);
ASSERT(args->type == XFS_ALLOCTYPE_NEAR_BNO);
*stat = 0;
error = xfs_alloc_lookup_le(acur->bnolt, args->agbno, 0, &i);
if (error)
return error;
error = xfs_alloc_lookup_ge(acur->bnogt, args->agbno, 0, &i);
if (error)
return error;
/*
* Loop going left with the leftward cursor, right with the rightward
* cursor, until either both directions give up or we find an entry at
* least as big as minlen.
*/
while (xfs_alloc_cur_active(acur->bnolt) ||
xfs_alloc_cur_active(acur->bnogt)) {
error = xfs_alloc_walk_iter(args, acur, acur->bnolt, false,
true, 1, &i);
if (error)
return error;
if (i == 1) {
trace_xfs_alloc_cur_left(args);
fbcur = acur->bnogt;
fbinc = true;
break;
}
error = xfs_alloc_walk_iter(args, acur, acur->bnogt, true, true,
1, &i);
if (error)
return error;
if (i == 1) {
trace_xfs_alloc_cur_right(args);
fbcur = acur->bnolt;
fbinc = false;
break;
}
}
/* search the opposite direction for a better entry */
if (fbcur) {
error = xfs_alloc_walk_iter(args, acur, fbcur, fbinc, true, -1,
&i);
if (error)
return error;
}
if (acur->len)
*stat = 1;
return 0;
}
/*
* Allocate a variable extent near bno in the allocation group agno.
* Extent's length (returned in len) will be between minlen and maxlen,
@ -1241,12 +1313,10 @@ xfs_alloc_ag_vextent_near(
struct xfs_alloc_arg *args)
{
struct xfs_alloc_cur acur = {};
struct xfs_btree_cur *fbcur = NULL;
int error; /* error code */
int i; /* result code, temporary */
xfs_agblock_t bno;
xfs_extlen_t len;
bool fbinc = false;
#ifdef DEBUG
/*
* Randomly don't execute the first algorithm.
@ -1348,61 +1418,11 @@ restart:
}
/*
* Second algorithm.
* Search in the by-bno tree to the left and to the right
* simultaneously, until in each case we find a space big enough,
* or run into the edge of the tree. When we run into the edge,
* we deallocate that cursor.
* If both searches succeed, we compare the two spaces and pick
* the better one.
* With alignment, it's possible for both to fail; the upper
* level algorithm that picks allocation groups for allocations
* is not supposed to do this.
* Second algorithm. Search the bnobt left and right.
*/
error = xfs_alloc_lookup_le(acur.bnolt, args->agbno, 0, &i);
error = xfs_alloc_ag_vextent_bnobt(args, &acur, &i);
if (error)
goto out;
error = xfs_alloc_lookup_ge(acur.bnogt, args->agbno, 0, &i);
if (error)
goto out;
/*
* Loop going left with the leftward cursor, right with the rightward
* cursor, until either both directions give up or we find an entry at
* least as big as minlen.
*/
do {
error = xfs_alloc_walk_iter(args, &acur, acur.bnolt, false,
true, 1, &i);
if (error)
goto out;
if (i == 1) {
trace_xfs_alloc_cur_left(args);
fbcur = acur.bnogt;
fbinc = true;
break;
}
error = xfs_alloc_walk_iter(args, &acur, acur.bnogt, true, true,
1, &i);
if (error)
goto out;
if (i == 1) {
trace_xfs_alloc_cur_right(args);
fbcur = acur.bnolt;
fbinc = false;
break;
}
} while (xfs_alloc_cur_active(acur.bnolt) ||
xfs_alloc_cur_active(acur.bnogt));
/* search the opposite direction for a better entry */
if (fbcur) {
error = xfs_alloc_walk_iter(args, &acur, fbcur, fbinc, true, -1,
&i);
if (error)
goto out;
}
/*
* If we couldn't get anything, give up.