diff options
Diffstat (limited to 'kernel/fs/xfs/xfs_filestream.c')
| -rw-r--r-- | kernel/fs/xfs/xfs_filestream.c | 431 |
1 files changed, 431 insertions, 0 deletions
diff --git a/kernel/fs/xfs/xfs_filestream.c b/kernel/fs/xfs/xfs_filestream.c new file mode 100644 index 000000000..da82f1cb4 --- /dev/null +++ b/kernel/fs/xfs/xfs_filestream.c @@ -0,0 +1,431 @@ +/* + * Copyright (c) 2006-2007 Silicon Graphics, Inc. + * Copyright (c) 2014 Christoph Hellwig. + * All Rights Reserved. + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License as + * published by the Free Software Foundation. + * + * This program is distributed in the hope that it would be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write the Free Software Foundation, + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA + */ +#include "xfs.h" +#include "xfs_format.h" +#include "xfs_log_format.h" +#include "xfs_trans_resv.h" +#include "xfs_sb.h" +#include "xfs_mount.h" +#include "xfs_inode.h" +#include "xfs_bmap.h" +#include "xfs_bmap_util.h" +#include "xfs_alloc.h" +#include "xfs_mru_cache.h" +#include "xfs_filestream.h" +#include "xfs_trace.h" + +struct xfs_fstrm_item { + struct xfs_mru_cache_elem mru; + struct xfs_inode *ip; + xfs_agnumber_t ag; /* AG in use for this directory */ +}; + +enum xfs_fstrm_alloc { + XFS_PICK_USERDATA = 1, + XFS_PICK_LOWSPACE = 2, +}; + +/* + * Allocation group filestream associations are tracked with per-ag atomic + * counters. These counters allow xfs_filestream_pick_ag() to tell whether a + * particular AG already has active filestreams associated with it. The mount + * point's m_peraglock is used to protect these counters from per-ag array + * re-allocation during a growfs operation. When xfs_growfs_data_private() is + * about to reallocate the array, it calls xfs_filestream_flush() with the + * m_peraglock held in write mode. + * + * Since xfs_mru_cache_flush() guarantees that all the free functions for all + * the cache elements have finished executing before it returns, it's safe for + * the free functions to use the atomic counters without m_peraglock protection. + * This allows the implementation of xfs_fstrm_free_func() to be agnostic about + * whether it was called with the m_peraglock held in read mode, write mode or + * not held at all. The race condition this addresses is the following: + * + * - The work queue scheduler fires and pulls a filestream directory cache + * element off the LRU end of the cache for deletion, then gets pre-empted. + * - A growfs operation grabs the m_peraglock in write mode, flushes all the + * remaining items from the cache and reallocates the mount point's per-ag + * array, resetting all the counters to zero. + * - The work queue thread resumes and calls the free function for the element + * it started cleaning up earlier. In the process it decrements the + * filestreams counter for an AG that now has no references. + * + * With a shrinkfs feature, the above scenario could panic the system. + * + * All other uses of the following macros should be protected by either the + * m_peraglock held in read mode, or the cache's internal locking exposed by the + * interval between a call to xfs_mru_cache_lookup() and a call to + * xfs_mru_cache_done(). In addition, the m_peraglock must be held in read mode + * when new elements are added to the cache. + * + * Combined, these locking rules ensure that no associations will ever exist in + * the cache that reference per-ag array elements that have since been + * reallocated. + */ +int +xfs_filestream_peek_ag( + xfs_mount_t *mp, + xfs_agnumber_t agno) +{ + struct xfs_perag *pag; + int ret; + + pag = xfs_perag_get(mp, agno); + ret = atomic_read(&pag->pagf_fstrms); + xfs_perag_put(pag); + return ret; +} + +static int +xfs_filestream_get_ag( + xfs_mount_t *mp, + xfs_agnumber_t agno) +{ + struct xfs_perag *pag; + int ret; + + pag = xfs_perag_get(mp, agno); + ret = atomic_inc_return(&pag->pagf_fstrms); + xfs_perag_put(pag); + return ret; +} + +static void +xfs_filestream_put_ag( + xfs_mount_t *mp, + xfs_agnumber_t agno) +{ + struct xfs_perag *pag; + + pag = xfs_perag_get(mp, agno); + atomic_dec(&pag->pagf_fstrms); + xfs_perag_put(pag); +} + +static void +xfs_fstrm_free_func( + struct xfs_mru_cache_elem *mru) +{ + struct xfs_fstrm_item *item = + container_of(mru, struct xfs_fstrm_item, mru); + + xfs_filestream_put_ag(item->ip->i_mount, item->ag); + + trace_xfs_filestream_free(item->ip, item->ag); + + kmem_free(item); +} + +/* + * 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( + struct xfs_inode *ip, + xfs_agnumber_t startag, + xfs_agnumber_t *agp, + int flags, + xfs_extlen_t minlen) +{ + struct xfs_mount *mp = ip->i_mount; + struct xfs_fstrm_item *item; + struct xfs_perag *pag; + xfs_extlen_t longest, free = 0, minfree, maxfree = 0; + xfs_agnumber_t ag, max_ag = NULLAGNUMBER; + int err, trylock, nscan; + + ASSERT(S_ISDIR(ip->i_d.di_mode)); + + /* 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_xfs_filestream_scan(ip, ag); + + pag = xfs_perag_get(mp, ag); + + 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_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; + 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); + free = maxfree; + *agp = max_ag; + break; + } + + /* take AG 0 if none matched */ + trace_xfs_filestream_pick(ip, *agp, free, nscan); + *agp = 0; + return 0; + } + + trace_xfs_filestream_pick(ip, *agp, free, nscan); + + if (*agp == NULLAGNUMBER) + return 0; + + err = -ENOMEM; + item = kmem_alloc(sizeof(*item), KM_MAYFAIL); + if (!item) + goto out_put_ag; + + item->ag = *agp; + item->ip = ip; + + err = xfs_mru_cache_insert(mp->m_filestream, ip->i_ino, &item->mru); + if (err) { + if (err == -EEXIST) + err = 0; + goto out_free_item; + } + + return 0; + +out_free_item: + kmem_free(item); +out_put_ag: + xfs_filestream_put_ag(mp, *agp); + return err; +} + +static struct xfs_inode * +xfs_filestream_get_parent( + struct xfs_inode *ip) +{ + struct inode *inode = VFS_I(ip), *dir = NULL; + struct dentry *dentry, *parent; + + dentry = d_find_alias(inode); + if (!dentry) + goto out; + + parent = dget_parent(dentry); + if (!parent) + goto out_dput; + + dir = igrab(d_inode(parent)); + dput(parent); + +out_dput: + dput(dentry); +out: + return dir ? XFS_I(dir) : NULL; +} + +/* + * Find the right allocation group for a file, either by finding an + * existing file stream or creating a new one. + * + * Returns NULLAGNUMBER in case of an error. + */ +xfs_agnumber_t +xfs_filestream_lookup_ag( + struct xfs_inode *ip) +{ + struct xfs_mount *mp = ip->i_mount; + struct xfs_inode *pip = NULL; + xfs_agnumber_t startag, ag = NULLAGNUMBER; + struct xfs_mru_cache_elem *mru; + + ASSERT(S_ISREG(ip->i_d.di_mode)); + + pip = xfs_filestream_get_parent(ip); + if (!pip) + return NULLAGNUMBER; + + mru = xfs_mru_cache_lookup(mp->m_filestream, pip->i_ino); + if (mru) { + ag = container_of(mru, struct xfs_fstrm_item, mru)->ag; + xfs_mru_cache_done(mp->m_filestream); + + trace_xfs_filestream_lookup(ip, ag); + goto out; + } + + /* + * Set the starting AG using the rotor for inode32, otherwise + * use the directory inode's AG. + */ + if (mp->m_flags & XFS_MOUNT_32BITINODES) { + xfs_agnumber_t rotorstep = xfs_rotorstep; + startag = (mp->m_agfrotor / rotorstep) % mp->m_sb.sb_agcount; + mp->m_agfrotor = (mp->m_agfrotor + 1) % + (mp->m_sb.sb_agcount * rotorstep); + } else + startag = XFS_INO_TO_AGNO(mp, pip->i_ino); + + if (xfs_filestream_pick_ag(pip, startag, &ag, 0, 0)) + ag = NULLAGNUMBER; +out: + IRELE(pip); + return ag; +} + +/* + * Pick a new allocation group for the current file and its file stream. + * + * This is called when the allocator can't find a suitable extent in the + * current AG, and we have to move the stream into a new AG with more space. + */ +int +xfs_filestream_new_ag( + struct xfs_bmalloca *ap, + xfs_agnumber_t *agp) +{ + struct xfs_inode *ip = ap->ip, *pip; + struct xfs_mount *mp = ip->i_mount; + xfs_extlen_t minlen = ap->length; + xfs_agnumber_t startag = 0; + int flags, err = 0; + struct xfs_mru_cache_elem *mru; + + *agp = NULLAGNUMBER; + + pip = xfs_filestream_get_parent(ip); + if (!pip) + goto exit; + + mru = xfs_mru_cache_remove(mp->m_filestream, pip->i_ino); + if (mru) { + struct xfs_fstrm_item *item = + container_of(mru, struct xfs_fstrm_item, mru); + startag = (item->ag + 1) % mp->m_sb.sb_agcount; + } + + flags = (ap->userdata ? XFS_PICK_USERDATA : 0) | + (ap->flist->xbf_low ? XFS_PICK_LOWSPACE : 0); + + err = xfs_filestream_pick_ag(pip, startag, agp, flags, minlen); + + /* + * Only free the item here so we skip over the old AG earlier. + */ + if (mru) + xfs_fstrm_free_func(mru); + + IRELE(pip); +exit: + if (*agp == NULLAGNUMBER) + *agp = 0; + return err; +} + +void +xfs_filestream_deassociate( + struct xfs_inode *ip) +{ + xfs_mru_cache_delete(ip->i_mount->m_filestream, ip->i_ino); +} + +int +xfs_filestream_mount( + xfs_mount_t *mp) +{ + /* + * The filestream timer tunable is currently fixed within the range of + * one second to four minutes, with five seconds being the default. The + * group count is somewhat arbitrary, but it'd be nice to adhere to the + * timer tunable to within about 10 percent. This requires at least 10 + * groups. + */ + return xfs_mru_cache_create(&mp->m_filestream, xfs_fstrm_centisecs * 10, + 10, xfs_fstrm_free_func); +} + +void +xfs_filestream_unmount( + xfs_mount_t *mp) +{ + xfs_mru_cache_destroy(mp->m_filestream); +} |