linux/fs/xfs/xfs_filestream.c
Dave Chinner 496817b4be xfs: clean up XFS_MIN_FREELIST macros
We no longer calculate the minimum freelist size from the on-disk
AGF, so we don't need the macros used for this. That means the
nested macros can be cleaned up, and turn this into an actual
function so the logic is clear and concise. This will make it much
easier to add support for the rmap btree when the time comes.

This also gets rid of the XFS_AG_MAXLEVELS macro used by these
freelist macros as it is simply a wrapper around a single variable.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
2015-06-22 10:13:30 +10:00

433 lines
11 KiB
C

/*
* 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,
xfs_alloc_min_freelist(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);
}