mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-26 02:39:48 +00:00
![Darrick J. Wong](/assets/img/avatar_default.png)
The new online shrink code exposed a gap in the per-AG reservation code, which is that we only return ENOSPC to callers if the entire fs doesn't have enough free blocks. Except for debugging mode, the reservation init code doesn't ever check that there's enough free space in that AG to cover the reservation. Not having enough space is not considered an immediate fatal error that requires filesystem offlining because (a) it's shouldn't be possible to wind up in that state through normal file operations and (b) even if one did, freeing data blocks would recover the situation. However, online shrink now needs to know if shrinking would not leave enough space so that it can abort the shrink operation. Hence we need to promote this assertion into an actual error return. Observed by running xfs/168 with a 1k block size, though in theory this could happen with any configuration. Signed-off-by: Darrick J. Wong <djwong@kernel.org> Reviewed-by: Brian Foster <bfoster@redhat.com> Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com> Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
426 lines
12 KiB
C
426 lines
12 KiB
C
// SPDX-License-Identifier: GPL-2.0+
|
|
/*
|
|
* Copyright (C) 2016 Oracle. All Rights Reserved.
|
|
* Author: Darrick J. Wong <darrick.wong@oracle.com>
|
|
*/
|
|
#include "xfs.h"
|
|
#include "xfs_fs.h"
|
|
#include "xfs_shared.h"
|
|
#include "xfs_format.h"
|
|
#include "xfs_log_format.h"
|
|
#include "xfs_trans_resv.h"
|
|
#include "xfs_mount.h"
|
|
#include "xfs_alloc.h"
|
|
#include "xfs_errortag.h"
|
|
#include "xfs_error.h"
|
|
#include "xfs_trace.h"
|
|
#include "xfs_trans.h"
|
|
#include "xfs_rmap_btree.h"
|
|
#include "xfs_btree.h"
|
|
#include "xfs_refcount_btree.h"
|
|
#include "xfs_ialloc_btree.h"
|
|
#include "xfs_sb.h"
|
|
#include "xfs_ag_resv.h"
|
|
|
|
/*
|
|
* Per-AG Block Reservations
|
|
*
|
|
* For some kinds of allocation group metadata structures, it is advantageous
|
|
* to reserve a small number of blocks in each AG so that future expansions of
|
|
* that data structure do not encounter ENOSPC because errors during a btree
|
|
* split cause the filesystem to go offline.
|
|
*
|
|
* Prior to the introduction of reflink, this wasn't an issue because the free
|
|
* space btrees maintain a reserve of space (the AGFL) to handle any expansion
|
|
* that may be necessary; and allocations of other metadata (inodes, BMBT,
|
|
* dir/attr) aren't restricted to a single AG. However, with reflink it is
|
|
* possible to allocate all the space in an AG, have subsequent reflink/CoW
|
|
* activity expand the refcount btree, and discover that there's no space left
|
|
* to handle that expansion. Since we can calculate the maximum size of the
|
|
* refcount btree, we can reserve space for it and avoid ENOSPC.
|
|
*
|
|
* Handling per-AG reservations consists of three changes to the allocator's
|
|
* behavior: First, because these reservations are always needed, we decrease
|
|
* the ag_max_usable counter to reflect the size of the AG after the reserved
|
|
* blocks are taken. Second, the reservations must be reflected in the
|
|
* fdblocks count to maintain proper accounting. Third, each AG must maintain
|
|
* its own reserved block counter so that we can calculate the amount of space
|
|
* that must remain free to maintain the reservations. Fourth, the "remaining
|
|
* reserved blocks" count must be used when calculating the length of the
|
|
* longest free extent in an AG and to clamp maxlen in the per-AG allocation
|
|
* functions. In other words, we maintain a virtual allocation via in-core
|
|
* accounting tricks so that we don't have to clean up after a crash. :)
|
|
*
|
|
* Reserved blocks can be managed by passing one of the enum xfs_ag_resv_type
|
|
* values via struct xfs_alloc_arg or directly to the xfs_free_extent
|
|
* function. It might seem a little funny to maintain a reservoir of blocks
|
|
* to feed another reservoir, but the AGFL only holds enough blocks to get
|
|
* through the next transaction. The per-AG reservation is to ensure (we
|
|
* hope) that each AG never runs out of blocks. Each data structure wanting
|
|
* to use the reservation system should update ask/used in xfs_ag_resv_init.
|
|
*/
|
|
|
|
/*
|
|
* Are we critically low on blocks? For now we'll define that as the number
|
|
* of blocks we can get our hands on being less than 10% of what we reserved
|
|
* or less than some arbitrary number (maximum btree height).
|
|
*/
|
|
bool
|
|
xfs_ag_resv_critical(
|
|
struct xfs_perag *pag,
|
|
enum xfs_ag_resv_type type)
|
|
{
|
|
xfs_extlen_t avail;
|
|
xfs_extlen_t orig;
|
|
|
|
switch (type) {
|
|
case XFS_AG_RESV_METADATA:
|
|
avail = pag->pagf_freeblks - pag->pag_rmapbt_resv.ar_reserved;
|
|
orig = pag->pag_meta_resv.ar_asked;
|
|
break;
|
|
case XFS_AG_RESV_RMAPBT:
|
|
avail = pag->pagf_freeblks + pag->pagf_flcount -
|
|
pag->pag_meta_resv.ar_reserved;
|
|
orig = pag->pag_rmapbt_resv.ar_asked;
|
|
break;
|
|
default:
|
|
ASSERT(0);
|
|
return false;
|
|
}
|
|
|
|
trace_xfs_ag_resv_critical(pag, type, avail);
|
|
|
|
/* Critically low if less than 10% or max btree height remains. */
|
|
return XFS_TEST_ERROR(avail < orig / 10 || avail < XFS_BTREE_MAXLEVELS,
|
|
pag->pag_mount, XFS_ERRTAG_AG_RESV_CRITICAL);
|
|
}
|
|
|
|
/*
|
|
* How many blocks are reserved but not used, and therefore must not be
|
|
* allocated away?
|
|
*/
|
|
xfs_extlen_t
|
|
xfs_ag_resv_needed(
|
|
struct xfs_perag *pag,
|
|
enum xfs_ag_resv_type type)
|
|
{
|
|
xfs_extlen_t len;
|
|
|
|
len = pag->pag_meta_resv.ar_reserved + pag->pag_rmapbt_resv.ar_reserved;
|
|
switch (type) {
|
|
case XFS_AG_RESV_METADATA:
|
|
case XFS_AG_RESV_RMAPBT:
|
|
len -= xfs_perag_resv(pag, type)->ar_reserved;
|
|
break;
|
|
case XFS_AG_RESV_NONE:
|
|
/* empty */
|
|
break;
|
|
default:
|
|
ASSERT(0);
|
|
}
|
|
|
|
trace_xfs_ag_resv_needed(pag, type, len);
|
|
|
|
return len;
|
|
}
|
|
|
|
/* Clean out a reservation */
|
|
static int
|
|
__xfs_ag_resv_free(
|
|
struct xfs_perag *pag,
|
|
enum xfs_ag_resv_type type)
|
|
{
|
|
struct xfs_ag_resv *resv;
|
|
xfs_extlen_t oldresv;
|
|
int error;
|
|
|
|
trace_xfs_ag_resv_free(pag, type, 0);
|
|
|
|
resv = xfs_perag_resv(pag, type);
|
|
if (pag->pag_agno == 0)
|
|
pag->pag_mount->m_ag_max_usable += resv->ar_asked;
|
|
/*
|
|
* RMAPBT blocks come from the AGFL and AGFL blocks are always
|
|
* considered "free", so whatever was reserved at mount time must be
|
|
* given back at umount.
|
|
*/
|
|
if (type == XFS_AG_RESV_RMAPBT)
|
|
oldresv = resv->ar_orig_reserved;
|
|
else
|
|
oldresv = resv->ar_reserved;
|
|
error = xfs_mod_fdblocks(pag->pag_mount, oldresv, true);
|
|
resv->ar_reserved = 0;
|
|
resv->ar_asked = 0;
|
|
resv->ar_orig_reserved = 0;
|
|
|
|
if (error)
|
|
trace_xfs_ag_resv_free_error(pag->pag_mount, pag->pag_agno,
|
|
error, _RET_IP_);
|
|
return error;
|
|
}
|
|
|
|
/* Free a per-AG reservation. */
|
|
int
|
|
xfs_ag_resv_free(
|
|
struct xfs_perag *pag)
|
|
{
|
|
int error;
|
|
int err2;
|
|
|
|
error = __xfs_ag_resv_free(pag, XFS_AG_RESV_RMAPBT);
|
|
err2 = __xfs_ag_resv_free(pag, XFS_AG_RESV_METADATA);
|
|
if (err2 && !error)
|
|
error = err2;
|
|
return error;
|
|
}
|
|
|
|
static int
|
|
__xfs_ag_resv_init(
|
|
struct xfs_perag *pag,
|
|
enum xfs_ag_resv_type type,
|
|
xfs_extlen_t ask,
|
|
xfs_extlen_t used)
|
|
{
|
|
struct xfs_mount *mp = pag->pag_mount;
|
|
struct xfs_ag_resv *resv;
|
|
int error;
|
|
xfs_extlen_t hidden_space;
|
|
|
|
if (used > ask)
|
|
ask = used;
|
|
|
|
switch (type) {
|
|
case XFS_AG_RESV_RMAPBT:
|
|
/*
|
|
* Space taken by the rmapbt is not subtracted from fdblocks
|
|
* because the rmapbt lives in the free space. Here we must
|
|
* subtract the entire reservation from fdblocks so that we
|
|
* always have blocks available for rmapbt expansion.
|
|
*/
|
|
hidden_space = ask;
|
|
break;
|
|
case XFS_AG_RESV_METADATA:
|
|
/*
|
|
* Space taken by all other metadata btrees are accounted
|
|
* on-disk as used space. We therefore only hide the space
|
|
* that is reserved but not used by the trees.
|
|
*/
|
|
hidden_space = ask - used;
|
|
break;
|
|
default:
|
|
ASSERT(0);
|
|
return -EINVAL;
|
|
}
|
|
|
|
if (XFS_TEST_ERROR(false, mp, XFS_ERRTAG_AG_RESV_FAIL))
|
|
error = -ENOSPC;
|
|
else
|
|
error = xfs_mod_fdblocks(mp, -(int64_t)hidden_space, true);
|
|
if (error) {
|
|
trace_xfs_ag_resv_init_error(pag->pag_mount, pag->pag_agno,
|
|
error, _RET_IP_);
|
|
xfs_warn(mp,
|
|
"Per-AG reservation for AG %u failed. Filesystem may run out of space.",
|
|
pag->pag_agno);
|
|
return error;
|
|
}
|
|
|
|
/*
|
|
* Reduce the maximum per-AG allocation length by however much we're
|
|
* trying to reserve for an AG. Since this is a filesystem-wide
|
|
* counter, we only make the adjustment for AG 0. This assumes that
|
|
* there aren't any AGs hungrier for per-AG reservation than AG 0.
|
|
*/
|
|
if (pag->pag_agno == 0)
|
|
mp->m_ag_max_usable -= ask;
|
|
|
|
resv = xfs_perag_resv(pag, type);
|
|
resv->ar_asked = ask;
|
|
resv->ar_orig_reserved = hidden_space;
|
|
resv->ar_reserved = ask - used;
|
|
|
|
trace_xfs_ag_resv_init(pag, type, ask);
|
|
return 0;
|
|
}
|
|
|
|
/* Create a per-AG block reservation. */
|
|
int
|
|
xfs_ag_resv_init(
|
|
struct xfs_perag *pag,
|
|
struct xfs_trans *tp)
|
|
{
|
|
struct xfs_mount *mp = pag->pag_mount;
|
|
xfs_agnumber_t agno = pag->pag_agno;
|
|
xfs_extlen_t ask;
|
|
xfs_extlen_t used;
|
|
int error = 0, error2;
|
|
bool has_resv = false;
|
|
|
|
/* Create the metadata reservation. */
|
|
if (pag->pag_meta_resv.ar_asked == 0) {
|
|
ask = used = 0;
|
|
|
|
error = xfs_refcountbt_calc_reserves(mp, tp, agno, &ask, &used);
|
|
if (error)
|
|
goto out;
|
|
|
|
error = xfs_finobt_calc_reserves(mp, tp, agno, &ask, &used);
|
|
if (error)
|
|
goto out;
|
|
|
|
error = __xfs_ag_resv_init(pag, XFS_AG_RESV_METADATA,
|
|
ask, used);
|
|
if (error) {
|
|
/*
|
|
* Because we didn't have per-AG reservations when the
|
|
* finobt feature was added we might not be able to
|
|
* reserve all needed blocks. Warn and fall back to the
|
|
* old and potentially buggy code in that case, but
|
|
* ensure we do have the reservation for the refcountbt.
|
|
*/
|
|
ask = used = 0;
|
|
|
|
mp->m_finobt_nores = true;
|
|
|
|
error = xfs_refcountbt_calc_reserves(mp, tp, agno, &ask,
|
|
&used);
|
|
if (error)
|
|
goto out;
|
|
|
|
error = __xfs_ag_resv_init(pag, XFS_AG_RESV_METADATA,
|
|
ask, used);
|
|
if (error)
|
|
goto out;
|
|
}
|
|
if (ask)
|
|
has_resv = true;
|
|
}
|
|
|
|
/* Create the RMAPBT metadata reservation */
|
|
if (pag->pag_rmapbt_resv.ar_asked == 0) {
|
|
ask = used = 0;
|
|
|
|
error = xfs_rmapbt_calc_reserves(mp, tp, agno, &ask, &used);
|
|
if (error)
|
|
goto out;
|
|
|
|
error = __xfs_ag_resv_init(pag, XFS_AG_RESV_RMAPBT, ask, used);
|
|
if (error)
|
|
goto out;
|
|
if (ask)
|
|
has_resv = true;
|
|
}
|
|
|
|
out:
|
|
/*
|
|
* Initialize the pagf if we have at least one active reservation on the
|
|
* AG. This may have occurred already via reservation calculation, but
|
|
* fall back to an explicit init to ensure the in-core allocbt usage
|
|
* counters are initialized as soon as possible. This is important
|
|
* because filesystems with large perag reservations are susceptible to
|
|
* free space reservation problems that the allocbt counter is used to
|
|
* address.
|
|
*/
|
|
if (has_resv) {
|
|
error2 = xfs_alloc_pagf_init(mp, tp, pag->pag_agno, 0);
|
|
if (error2)
|
|
return error2;
|
|
|
|
/*
|
|
* If there isn't enough space in the AG to satisfy the
|
|
* reservation, let the caller know that there wasn't enough
|
|
* space. Callers are responsible for deciding what to do
|
|
* next, since (in theory) we can stumble along with
|
|
* insufficient reservation if data blocks are being freed to
|
|
* replenish the AG's free space.
|
|
*/
|
|
if (!error &&
|
|
xfs_perag_resv(pag, XFS_AG_RESV_METADATA)->ar_reserved +
|
|
xfs_perag_resv(pag, XFS_AG_RESV_RMAPBT)->ar_reserved >
|
|
pag->pagf_freeblks + pag->pagf_flcount)
|
|
error = -ENOSPC;
|
|
}
|
|
|
|
return error;
|
|
}
|
|
|
|
/* Allocate a block from the reservation. */
|
|
void
|
|
xfs_ag_resv_alloc_extent(
|
|
struct xfs_perag *pag,
|
|
enum xfs_ag_resv_type type,
|
|
struct xfs_alloc_arg *args)
|
|
{
|
|
struct xfs_ag_resv *resv;
|
|
xfs_extlen_t len;
|
|
uint field;
|
|
|
|
trace_xfs_ag_resv_alloc_extent(pag, type, args->len);
|
|
|
|
switch (type) {
|
|
case XFS_AG_RESV_AGFL:
|
|
return;
|
|
case XFS_AG_RESV_METADATA:
|
|
case XFS_AG_RESV_RMAPBT:
|
|
resv = xfs_perag_resv(pag, type);
|
|
break;
|
|
default:
|
|
ASSERT(0);
|
|
/* fall through */
|
|
case XFS_AG_RESV_NONE:
|
|
field = args->wasdel ? XFS_TRANS_SB_RES_FDBLOCKS :
|
|
XFS_TRANS_SB_FDBLOCKS;
|
|
xfs_trans_mod_sb(args->tp, field, -(int64_t)args->len);
|
|
return;
|
|
}
|
|
|
|
len = min_t(xfs_extlen_t, args->len, resv->ar_reserved);
|
|
resv->ar_reserved -= len;
|
|
if (type == XFS_AG_RESV_RMAPBT)
|
|
return;
|
|
/* Allocations of reserved blocks only need on-disk sb updates... */
|
|
xfs_trans_mod_sb(args->tp, XFS_TRANS_SB_RES_FDBLOCKS, -(int64_t)len);
|
|
/* ...but non-reserved blocks need in-core and on-disk updates. */
|
|
if (args->len > len)
|
|
xfs_trans_mod_sb(args->tp, XFS_TRANS_SB_FDBLOCKS,
|
|
-((int64_t)args->len - len));
|
|
}
|
|
|
|
/* Free a block to the reservation. */
|
|
void
|
|
xfs_ag_resv_free_extent(
|
|
struct xfs_perag *pag,
|
|
enum xfs_ag_resv_type type,
|
|
struct xfs_trans *tp,
|
|
xfs_extlen_t len)
|
|
{
|
|
xfs_extlen_t leftover;
|
|
struct xfs_ag_resv *resv;
|
|
|
|
trace_xfs_ag_resv_free_extent(pag, type, len);
|
|
|
|
switch (type) {
|
|
case XFS_AG_RESV_AGFL:
|
|
return;
|
|
case XFS_AG_RESV_METADATA:
|
|
case XFS_AG_RESV_RMAPBT:
|
|
resv = xfs_perag_resv(pag, type);
|
|
break;
|
|
default:
|
|
ASSERT(0);
|
|
/* fall through */
|
|
case XFS_AG_RESV_NONE:
|
|
xfs_trans_mod_sb(tp, XFS_TRANS_SB_FDBLOCKS, (int64_t)len);
|
|
return;
|
|
}
|
|
|
|
leftover = min_t(xfs_extlen_t, len, resv->ar_asked - resv->ar_reserved);
|
|
resv->ar_reserved += leftover;
|
|
if (type == XFS_AG_RESV_RMAPBT)
|
|
return;
|
|
/* Freeing into the reserved pool only requires on-disk update... */
|
|
xfs_trans_mod_sb(tp, XFS_TRANS_SB_RES_FDBLOCKS, len);
|
|
/* ...but freeing beyond that requires in-core and on-disk update. */
|
|
if (len > leftover)
|
|
xfs_trans_mod_sb(tp, XFS_TRANS_SB_FDBLOCKS, len - leftover);
|
|
}
|