linux/fs/xfs/xfs_filestream.c
Christoph Hellwig 785ce41805 xfs: tell lockdep about parent iolock usage in filestreams
The filestreams code may take the iolock on the parent inode while
holding it on a child.  This is the only place in XFS where we take
both the child and parent iolock, so just telling lockdep about it
is enough.  The lock flag required for that was already added as
part of the ilock lockdep annotations and unused so far.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Alex Elder <aelder@sgi.com>
2010-11-10 12:00:48 -06:00

824 lines
23 KiB
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 && (((ip->i_d.di_mode & S_IFREG) && pip &&
(pip->i_d.di_mode & S_IFDIR)) ||
((ip->i_d.di_mode & S_IFDIR) && !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 (!(ip->i_d.di_mode & (S_IFREG | S_IFDIR))) {
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(pip->i_d.di_mode & S_IFDIR);
ASSERT(ip->i_d.di_mode & S_IFREG);
if (!(pip->i_d.di_mode & S_IFDIR) || !(ip->i_d.di_mode & S_IFREG))
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->alen;
*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->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);
}