int
xfs_min_freelist_pag(xfs_perag_t *pag, xfs_mount_t *mp)
{
return XFS_MIN_FREELIST_PAG(pag, mp);
}
/*
* Scan the AGs starting at startag looking for an AG that isn't in use and has
* at least minlen blocks free.
*/
static int
_xfs_filestream_pick_ag(
xfs_mount_t *mp,
xfs_agnumber_t startag,
xfs_agnumber_t *agp,
int flags,
xfs_extlen_t minlen)
{
int err, trylock, nscan;
xfs_extlen_t delta, longest, need, free, minfree, maxfree = 0;
xfs_agnumber_t ag, max_ag = NULLAGNUMBER;
struct xfs_perag *pag;
/* 2% of an AG's blocks must be free for it to be chosen. */
minfree = mp->m_sb.sb_agblocks / 50;
ag = startag;
*agp = NULLAGNUMBER;
/* For the first pass, don't sleep trying to init the per-AG. */
trylock = XFS_ALLOC_FLAG_TRYLOCK;
for (nscan = 0; 1; nscan++) {
TRACE_AG_SCAN(mp, ag, xfs_filestream_peek_ag(mp, ag));
pag = mp->m_perag + ag;
if (!pag->pagf_init) {
err = xfs_alloc_pagf_init(mp, NULL, ag, trylock);
if (err && !trylock)
return err;
}
/* Might fail sometimes during the 1st pass with trylock set. */
if (!pag->pagf_init)
goto next_ag;
/* Keep track of the AG with the most free blocks. */
if (pag->pagf_freeblks > maxfree) {
maxfree = pag->pagf_freeblks;
max_ag = ag;
}
/*
* The AG reference count does two things: it enforces mutual
* exclusion when examining the suitability of an AG in this
* loop, and it guards against two filestreams being established
* in the same AG as each other.
*/
if (xfs_filestream_get_ag(mp, ag) > 1) {
xfs_filestream_put_ag(mp, ag);
goto next_ag;
}
need = XFS_MIN_FREELIST_PAG(pag, mp);
delta = need > pag->pagf_flcount ? need - pag->pagf_flcount : 0;
longest = (pag->pagf_longest > delta) ?
(pag->pagf_longest - delta) :
(pag->pagf_flcount > 0 || pag->pagf_longest > 0);
if (((minlen && longest >= minlen) ||
(!minlen && pag->pagf_freeblks >= minfree)) &&
(!pag->pagf_metadata || !(flags & XFS_PICK_USERDATA) ||
(flags & XFS_PICK_LOWSPACE))) {
/* Break out, retaining the reference on the AG. */
free = pag->pagf_freeblks;
*agp = ag;
break;
}
/* Drop the reference on this AG, it's not usable. */
xfs_filestream_put_ag(mp, ag);
next_ag:
/* Move to the next AG, wrapping to AG 0 if necessary. */
if (++ag >= mp->m_sb.sb_agcount)
ag = 0;
/* If a full pass of the AGs hasn't been done yet, continue. */
if (ag != startag)
continue;
/* Allow sleeping in xfs_alloc_pagf_init() on the 2nd pass. */
if (trylock != 0) {
trylock = 0;
continue;
}
/* Finally, if lowspace wasn't set, set it for the 3rd pass. */
if (!(flags & XFS_PICK_LOWSPACE)) {
flags |= XFS_PICK_LOWSPACE;
continue;
}
/*
* Take the AG with the most free space, regardless of whether
* it's already in use by another filestream.
*/
if (max_ag != NULLAGNUMBER) {
xfs_filestream_get_ag(mp, max_ag);
TRACE_AG_PICK1(mp, max_ag, maxfree);
free = maxfree;
*agp = max_ag;
break;
}
/* take AG 0 if none matched */
TRACE_AG_PICK1(mp, max_ag, maxfree);
*agp = 0;
return 0;
}
TRACE_AG_PICK2(mp, startag, *agp, xfs_filestream_peek_ag(mp, *agp),
free, nscan, flags);
return 0;
}
