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 streams, max_streams; int err, trylock, nscan; xfs_extlen_t longest, 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++) { pag = xfs_perag_get(mp, ag); TRACE_AG_SCAN(mp, ag, atomic_read(&pag->pagf_fstrms)); if (!pag->pagf_init) { err = xfs_alloc_pagf_init(mp, NULL, ag, trylock); if (err && !trylock) { xfs_perag_put(pag); 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_streams = atomic_read(&pag->pagf_fstrms); 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; } longest = xfs_alloc_longest_free_extent(mp, pag); 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; streams = atomic_read(&pag->pagf_fstrms); xfs_perag_put(pag); *agp = ag; break; } /* Drop the reference on this AG, it's not usable. */ xfs_filestream_put_ag(mp, ag); next_ag: xfs_perag_put(pag); /* 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); streams = max_streams; 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, streams, free, nscan, flags); return 0; }
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 streams, max_streams; int err, trylock, nscan; xfs_extlen_t longest, free, minfree, maxfree = 0; xfs_agnumber_t ag, max_ag = NULLAGNUMBER; struct xfs_perag *pag; minfree = mp->m_sb.sb_agblocks / 50; ag = startag; *agp = NULLAGNUMBER; trylock = XFS_ALLOC_FLAG_TRYLOCK; for (nscan = 0; 1; nscan++) { pag = xfs_perag_get(mp, ag); TRACE_AG_SCAN(mp, ag, atomic_read(&pag->pagf_fstrms)); if (!pag->pagf_init) { err = xfs_alloc_pagf_init(mp, NULL, ag, trylock); if (err && !trylock) { xfs_perag_put(pag); return err; } } if (!pag->pagf_init) goto next_ag; if (pag->pagf_freeblks > maxfree) { maxfree = pag->pagf_freeblks; max_streams = atomic_read(&pag->pagf_fstrms); max_ag = ag; } if (xfs_filestream_get_ag(mp, ag) > 1) { xfs_filestream_put_ag(mp, ag); goto next_ag; } longest = xfs_alloc_longest_free_extent(mp, pag); if (((minlen && longest >= minlen) || (!minlen && pag->pagf_freeblks >= minfree)) && (!pag->pagf_metadata || !(flags & XFS_PICK_USERDATA) || (flags & XFS_PICK_LOWSPACE))) { free = pag->pagf_freeblks; streams = atomic_read(&pag->pagf_fstrms); xfs_perag_put(pag); *agp = ag; break; } xfs_filestream_put_ag(mp, ag); next_ag: xfs_perag_put(pag); if (++ag >= mp->m_sb.sb_agcount) ag = 0; if (ag != startag) continue; if (trylock != 0) { trylock = 0; continue; } if (!(flags & XFS_PICK_LOWSPACE)) { flags |= XFS_PICK_LOWSPACE; continue; } if (max_ag != NULLAGNUMBER) { xfs_filestream_get_ag(mp, max_ag); TRACE_AG_PICK1(mp, max_ag, maxfree); streams = max_streams; free = maxfree; *agp = max_ag; break; } TRACE_AG_PICK1(mp, max_ag, maxfree); *agp = 0; return 0; } TRACE_AG_PICK2(mp, startag, *agp, streams, free, nscan, flags); return 0; }