- 根目录:
- fs
- xfs
- xfs_filestream.c
/*
* Copyright (c) 2006-2007 Silicon Graphics, Inc.
* 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_bmap_btree.h"
#include "xfs_inum.h"
#include "xfs_dinode.h"
#include "xfs_inode.h"
#include "xfs_ag.h"
#include "xfs_log.h"
#include "xfs_trans.h"
#include "xfs_sb.h"
#include "xfs_mount.h"
#include "xfs_bmap.h"
#include "xfs_alloc.h"
#include "xfs_utils.h"
#include "xfs_mru_cache.h"
#include "xfs_filestream.h"
#include "xfs_trace.h"
#ifdef XFS_FILESTREAMS_TRACE
ktrace_t *xfs_filestreams_trace_buf;
STATIC void
xfs_filestreams_trace(
xfs_mount_t *mp, /* mount point */
int type, /* type of trace */
const char *func, /* source function */
int line, /* source line number */
__psunsigned_t arg0,
__psunsigned_t arg1,
__psunsigned_t arg2,
__psunsigned_t arg3,
__psunsigned_t arg4,
__psunsigned_t arg5)
{
ktrace_enter(xfs_filestreams_trace_buf,
(void *)(__psint_t)(type | (line << 16)),
(void *)func,
(void *)(__psunsigned_t)current_pid(),
(void *)mp,
(void *)(__psunsigned_t)arg0,
(void *)(__psunsigned_t)arg1,
(void *)(__psunsigned_t)arg2,
(void *)(__psunsigned_t)arg3,
(void *)(__psunsigned_t)arg4,
(void *)(__psunsigned_t)arg5,
NULL, NULL, NULL, NULL, NULL, NULL);
}
#define TRACE0(mp,t) TRACE6(mp,t,0,0,0,0,0,0)
#define TRACE1(mp,t,a0) TRACE6(mp,t,a0,0,0,0,0,0)
#define TRACE2(mp,t,a0,a1) TRACE6(mp,t,a0,a1,0,0,0,0)
#define TRACE3(mp,t,a0,a1,a2) TRACE6(mp,t,a0,a1,a2,0,0,0)
#define TRACE4(mp,t,a0,a1,a2,a3) TRACE6(mp,t,a0,a1,a2,a3,0,0)
#define TRACE5(mp,t,a0,a1,a2,a3,a4) TRACE6(mp,t,a0,a1,a2,a3,a4,0)
#define TRACE6(mp,t,a0,a1,a2,a3,a4,a5) \
xfs_filestreams_trace(mp, t, __func__, __LINE__, \
(__psunsigned_t)a0, (__psunsigned_t)a1, \
(__psunsigned_t)a2, (__psunsigned_t)a3, \
(__psunsigned_t)a4, (__psunsigned_t)a5)
#define TRACE_AG_SCAN(mp, ag, ag2) \
TRACE2(mp, XFS_FSTRM_KTRACE_AGSCAN, ag, ag2);
#define TRACE_AG_PICK1(mp, max_ag, maxfree) \
TRACE2(mp, XFS_FSTRM_KTRACE_AGPICK1, max_ag, maxfree);
#define TRACE_AG_PICK2(mp, ag, ag2, cnt, free, scan, flag) \
TRACE6(mp, XFS_FSTRM_KTRACE_AGPICK2, ag, ag2, \
cnt, free, scan, flag)
#define TRACE_UPDATE(mp, ip, ag, cnt, ag2, cnt2) \
TRACE5(mp, XFS_FSTRM_KTRACE_UPDATE, ip, ag, cnt, ag2, cnt2)
#define TRACE_FREE(mp, ip, pip, ag, cnt) \
TRACE4(mp, XFS_FSTRM_KTRACE_FREE, ip, pip, ag, cnt)
#define TRACE_LOOKUP(mp, ip, pip, ag, cnt) \
TRACE4(mp, XFS_FSTRM_KTRACE_ITEM_LOOKUP, ip, pip, ag, cnt)
#define TRACE_ASSOCIATE(mp, ip, pip, ag, cnt) \
TRACE4(mp, XFS_FSTRM_KTRACE_ASSOCIATE, ip, pip, ag, cnt)
#define TRACE_MOVEAG(mp, ip, pip, oag, ocnt, nag, ncnt) \
TRACE6(mp, XFS_FSTRM_KTRACE_MOVEAG, ip, pip, oag, ocnt, nag, ncnt)
#define TRACE_ORPHAN(mp, ip, ag) \
TRACE2(mp, XFS_FSTRM_KTRACE_ORPHAN, ip, ag);
#else
#define TRACE_AG_SCAN(mp, ag, ag2)
#define TRACE_AG_PICK1(mp, max_ag, maxfree)
#define TRACE_AG_PICK2(mp, ag, ag2, cnt, free, scan, flag)
#define TRACE_UPDATE(mp, ip, ag, cnt, ag2, cnt2)
#define TRACE_FREE(mp, ip, pip, ag, cnt)
#define TRACE_LOOKUP(mp, ip, pip, ag, cnt)
#define TRACE_ASSOCIATE(mp, ip, pip, ag, cnt)
#define TRACE_MOVEAG(mp, ip, pip, oag, ocnt, nag, ncnt)
#define TRACE_ORPHAN(mp, ip, ag)
#endif
static kmem_zone_t *item_zone;
/*
* Structure for associating a file or a directory with an allocation group.
* The parent directory pointer is only needed for files, but since there will
* generally be vastly more files than directories in the cache, using the same
* data structure simplifies the code with very little memory overhead.
*/
typedef struct fstrm_item
{
xfs_agnumber_t ag; /* AG currently in use for the file/directory. */
xfs_inode_t *ip; /* inode self-pointer. */
xfs_inode_t *pip; /* Parent directory inode pointer. */
} fstrm_item_t;
/*
* 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.
*/
static 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);
}
/*
* 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 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;
}
/*
* Set the allocation group number for a file or a directory, updating inode
* references and per-AG references as appropriate.
*/
static int
_xfs_filestream_update_ag(
xfs_inode_t *ip,
xfs_inode_t *pip,
xfs_agnumber_t ag)
{
int err = 0;
xfs_mount_t *mp;
xfs_mru_cache_t *cache;
fstrm_item_t *item;
xfs_agnumber_t old_ag;
xfs_inode_t *old_pip;
/*
* Either ip is a regular file and pip is a directory, or ip is a
* directory and pip is NULL.
*/
ASSERT(ip && ((S_ISREG(ip->i_d.di_mode) && pip &&
S_ISDIR(pip->i_d.di_mode)) ||
(S_ISDIR(ip->i_d.di_mode) && !pip)));
mp = ip->i_mount;
cache = mp->m_filestream;
item = xfs_mru_cache_lookup(cache, ip->i_ino);
if (item) {
ASSERT(item->ip == ip);
old_ag = item->ag;
item->ag = ag;
old_pip = item->pip;
item->pip = pip;
xfs_mru_cache_done(cache);
/*
* If the AG has changed, drop the old ref and take a new one,
* effectively transferring the reference from old to new AG.
*/
if (ag != old_ag) {
xfs_filestream_put_ag(mp, old_ag);
xfs_filestream_get_ag(mp, ag);
}
/*
* If ip is a file and its pip has changed, drop the old ref and
* take a new one.
*/
if (pip && pip != old_pip) {
IRELE(old_pip);
IHOLD(pip);
}
TRACE_UPDATE(mp, ip, old_ag, xfs_filestream_peek_ag(mp, old_ag),
ag, xfs_filestream_peek_ag(mp, ag));
return 0;
}
item = kmem_zone_zalloc(item_zone, KM_MAYFAIL);
if (!item)
return ENOMEM;
item->ag = ag;
item->ip = ip;
item->pip = pip;
err = xfs_mru_cache_insert(cache, ip->i_ino, item);
if (err) {
kmem_zone_free(item_zone, item);
return err;
}
/* Take a reference on the AG. */
xfs_filestream_get_ag(mp, ag);
/*
* Take a reference on the inode itself regardless of whether it's a
* regular file or a directory.
*/
IHOLD(ip);
/*
* In the case of a regular file, take a reference on the parent inode
* as well to ensure it remains in-core.
*/
if (pip)
IHOLD(pip);
TRACE_UPDATE(mp, ip, ag, xfs_filestream_peek_ag(mp, ag),
ag, xfs_filestream_peek_ag(mp, ag));
return 0;
}
/* xfs_fstrm_free_func(): callback for freeing cached stream items. */
STATIC void
xfs_fstrm_free_func(
unsigned long ino,
void *data)
{
fstrm_item_t *item = (fstrm_item_t *)data;
xfs_inode_t *ip = item->ip;
ASSERT(ip->i_ino == ino);
xfs_iflags_clear(ip, XFS_IFILESTREAM);
/* Drop the reference taken on the AG when the item was added. */
xfs_filestream_put_ag(ip->i_mount, item->ag);
TRACE_FREE(ip->i_mount, ip, item->pip, item->ag,
xfs_filestream_peek_ag(ip->i_mount, item->ag));
/*
* _xfs_filestream_update_ag() always takes a reference on the inode
* itself, whether it's a file or a directory. Release it here.
* This can result in the inode being freed and so we must
* not hold any inode locks when freeing filesstreams objects
* otherwise we can deadlock here.
*/
IRELE(ip);
/*
* In the case of a regular file, _xfs_filestream_update_ag() also
* takes a ref on the parent inode to keep it in-core. Release that
* too.
*/
if (item->pip)
IRELE(item->pip);
/* Finally, free the memory allocated for the item. */
kmem_zone_free(item_zone, item);
}
/*
* xfs_filestream_init() is called at xfs initialisation time to set up the
* memory zone that will be used for filestream data structure allocation.
*/
int
xfs_filestream_init(void)
{
item_zone = kmem_zone_init(sizeof(fstrm_item_t), "fstrm_item");
if (!item_zone)
return -ENOMEM;
return 0;
}
/*
* xfs_filestream_uninit() is called at xfs termination time to destroy the
* memory zone that was used for filestream data structure allocation.
*/
void
xfs_filestream_uninit(void)
{
kmem_zone_destroy(item_zone);
}
/*
* xfs_filestream_mount() is called when a file system is mounted with the
* filestream option. It is responsible for allocating the data structures
* needed to track the new file system's file streams.
*/
int
xfs_filestream_mount(
xfs_mount_t *mp)
{
int err;
unsigned int lifetime, grp_count;
/*
* 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.
*/
lifetime = xfs_fstrm_centisecs * 10;
grp_count = 10;
err = xfs_mru_cache_create(&mp->m_filestream, lifetime, grp_count,
xfs_fstrm_free_func);
return err;
}
/*
* xfs_filestream_unmount() is called when a file system that was mounted with
* the filestream option is unmounted. It drains the data structures created
* to track the file system's file streams and frees all the memory that was
* allocated.
*/
void
xfs_filestream_unmount(
xfs_mount_t *mp)
{
xfs_mru_cache_destroy(mp->m_filestream);
}
/*
* Return the AG of the filestream the file or directory belongs to, or
* NULLAGNUMBER otherwise.
*/
xfs_agnumber_t
xfs_filestream_lookup_ag(
xfs_inode_t *ip)
{
xfs_mru_cache_t *cache;
fstrm_item_t *item;
xfs_agnumber_t ag;
int ref;
if (!S_ISREG(ip->i_d.di_mode) && !S_ISDIR(ip->i_d.di_mode)) {
ASSERT(0);
return NULLAGNUMBER;
}
cache = ip->i_mount->m_filestream;
item = xfs_mru_cache_lookup(cache, ip->i_ino);
if (!item) {
TRACE_LOOKUP(ip->i_mount, ip, NULL, NULLAGNUMBER, 0);
return NULLAGNUMBER;
}
ASSERT(ip == item->ip);
ag = item->ag;
ref = xfs_filestream_peek_ag(ip->i_mount, ag);
xfs_mru_cache_done(cache);
TRACE_LOOKUP(ip->i_mount, ip, item->pip, ag, ref);
return ag;
}
/*
* xfs_filestream_associate() should only be called to associate a regular file
* with its parent directory. Calling it with a child directory isn't
* appropriate because filestreams don't apply to entire directory hierarchies.
* Creating a file in a child directory of an existing filestream directory
* starts a new filestream with its own allocation group association.
*
* Returns < 0 on error, 0 if successful association occurred, > 0 if
* we failed to get an association because of locking issues.
*/
int
xfs_filestream_associate(
xfs_inode_t *pip,
xfs_inode_t *ip)
{
xfs_mount_t *mp;
xfs_mru_cache_t *cache;
fstrm_item_t *item;
xfs_agnumber_t ag, rotorstep, startag;
int err = 0;
ASSERT(S_ISDIR(pip->i_d.di_mode));
ASSERT(S_ISREG(ip->i_d.di_mode));
if (!S_ISDIR(pip->i_d.di_mode) || !S_ISREG(ip->i_d.di_mode))
return -EINVAL;
mp = pip->i_mount;
cache = mp->m_filestream;
/*
* We have a problem, Houston.
*
* Taking the iolock here violates inode locking order - we already
* hold the ilock. Hence if we block getting this lock we may never
* wake. Unfortunately, that means if we can't get the lock, we're
* screwed in terms of getting a stream association - we can't spin
* waiting for the lock because someone else is waiting on the lock we
* hold and we cannot drop that as we are in a transaction here.
*
* Lucky for us, this inversion is not a problem because it's a
* directory inode that we are trying to lock here.
*
* So, if we can't get the iolock without sleeping then just give up
*/
if (!xfs_ilock_nowait(pip, XFS_IOLOCK_EXCL))
return 1;
/* If the parent directory is already in the cache, use its AG. */
item = xfs_mru_cache_lookup(cache, pip->i_ino);
if (item) {
ASSERT(item->ip == pip);
ag = item->ag;
xfs_mru_cache_done(cache);
TRACE_LOOKUP(mp, pip, pip, ag, xfs_filestream_peek_ag(mp, ag));
err = _xfs_filestream_update_ag(ip, pip, ag);
goto exit;
}
/*
* Set the starting AG using the rotor for inode32, otherwise
* use the directory inode's AG.
*/
if (mp->m_flags & XFS_MOUNT_32BITINODES) {
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);
/* Pick a new AG for the parent inode starting at startag. */
err = _xfs_filestream_pick_ag(mp, startag, &ag, 0, 0);
if (err || ag == NULLAGNUMBER)
goto exit_did_pick;
/* Associate the parent inode with the AG. */
err = _xfs_filestream_update_ag(pip, NULL, ag);
if (err)
goto exit_did_pick;
/* Associate the file inode with the AG. */
err = _xfs_filestream_update_ag(ip, pip, ag);
if (err)
goto exit_did_pick;
TRACE_ASSOCIATE(mp, ip, pip, ag, xfs_filestream_peek_ag(mp, ag));
exit_did_pick:
/*
* If _xfs_filestream_pick_ag() returned a valid AG, remove the
* reference it took on it, since the file and directory will have taken
* their own now if they were successfully cached.
*/
if (ag != NULLAGNUMBER)
xfs_filestream_put_ag(mp, ag);
exit:
xfs_iunlock(pip, XFS_IOLOCK_EXCL);
return -err;
}
/*
* Pick a new allocation group for the current file and its file stream. This
* function is called by xfs_bmap_filestreams() with the mount point's per-ag
* lock held.
*/
int
xfs_filestream_new_ag(
xfs_bmalloca_t *ap,
xfs_agnumber_t *agp)
{
int flags, err;
xfs_inode_t *ip, *pip = NULL;
xfs_mount_t *mp;
xfs_mru_cache_t *cache;
xfs_extlen_t minlen;
fstrm_item_t *dir, *file;
xfs_agnumber_t ag = NULLAGNUMBER;
ip = ap->ip;
mp = ip->i_mount;
cache = mp->m_filestream;
minlen = ap->length;
*agp = NULLAGNUMBER;
/*
* Look for the file in the cache, removing it if it's found. Doing
* this allows it to be held across the dir lookup that follows.
*/
file = xfs_mru_cache_remove(cache, ip->i_ino);
if (file) {
ASSERT(ip == file->ip);
/* Save the file's parent inode and old AG number for later. */
pip = file->pip;
ag = file->ag;
/* Look for the file's directory in the cache. */
dir = xfs_mru_cache_lookup(cache, pip->i_ino);
if (dir) {
ASSERT(pip == dir->ip);
/*
* If the directory has already moved on to a new AG,
* use that AG as the new AG for the file. Don't
* forget to twiddle the AG refcounts to match the
* movement.
*/
if (dir->ag != file->ag) {
xfs_filestream_put_ag(mp, file->ag);
xfs_filestream_get_ag(mp, dir->ag);
*agp = file->ag = dir->ag;
}
xfs_mru_cache_done(cache);
}
/*
* Put the file back in the cache. If this fails, the free
* function needs to be called to tidy up in the same way as if
* the item had simply expired from the cache.
*/
err = xfs_mru_cache_insert(cache, ip->i_ino, file);
if (err) {
xfs_fstrm_free_func(ip->i_ino, file);
return err;
}
/*
* If the file's AG was moved to the directory's new AG, there's
* nothing more to be done.
*/
if (*agp != NULLAGNUMBER) {
TRACE_MOVEAG(mp, ip, pip,
ag, xfs_filestream_peek_ag(mp, ag),
*agp, xfs_filestream_peek_ag(mp, *agp));
return 0;
}
}
/*
* If the file's parent directory is known, take its iolock in exclusive
* mode to prevent two sibling files from racing each other to migrate
* themselves and their parent to different AGs.
*
* Note that we lock the parent directory iolock inside the child
* iolock here. That's fine as we never hold both parent and child
* iolock in any other place. This is different from the ilock,
* which requires locking of the child after the parent for namespace
* operations.
*/
if (pip)
xfs_ilock(pip, XFS_IOLOCK_EXCL | XFS_IOLOCK_PARENT);
/*
* A new AG needs to be found for the file. If the file's parent
* directory is also known, it will be moved to the new AG as well to
* ensure that files created inside it in future use the new AG.
*/
ag = (ag == NULLAGNUMBER) ? 0 : (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(mp, ag, agp, flags, minlen);
if (err || *agp == NULLAGNUMBER)
goto exit;
/*
* If the file wasn't found in the file cache, then its parent directory
* inode isn't known. For this to have happened, the file must either
* be pre-existing, or it was created long enough ago that its cache
* entry has expired. This isn't the sort of usage that the filestreams
* allocator is trying to optimise, so there's no point trying to track
* its new AG somehow in the filestream data structures.
*/
if (!pip) {
TRACE_ORPHAN(mp, ip, *agp);
goto exit;
}
/* Associate the parent inode with the AG. */
err = _xfs_filestream_update_ag(pip, NULL, *agp);
if (err)
goto exit;
/* Associate the file inode with the AG. */
err = _xfs_filestream_update_ag(ip, pip, *agp);
if (err)
goto exit;
TRACE_MOVEAG(mp, ip, pip, NULLAGNUMBER, 0,
*agp, xfs_filestream_peek_ag(mp, *agp));
exit:
/*
* If _xfs_filestream_pick_ag() returned a valid AG, remove the
* reference it took on it, since the file and directory will have taken
* their own now if they were successfully cached.
*/
if (*agp != NULLAGNUMBER)
xfs_filestream_put_ag(mp, *agp);
else
*agp = 0;
if (pip)
xfs_iunlock(pip, XFS_IOLOCK_EXCL);
return err;
}
/*
* Remove an association between an inode and a filestream object.
* Typically this is done on last close of an unlinked file.
*/
void
xfs_filestream_deassociate(
xfs_inode_t *ip)
{
xfs_mru_cache_t *cache = ip->i_mount->m_filestream;
xfs_mru_cache_delete(cache, ip->i_ino);
}