// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (c) 2000-2006 Silicon Graphics, Inc.
* All Rights Reserved.
*/
#include "xfs.h"
#include <linux/backing-dev.h>
#include <linux/dax.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_trace.h"
#include "xfs_log.h"
#include "xfs_log_recover.h"
#include "xfs_log_priv.h"
#include "xfs_trans.h"
#include "xfs_buf_item.h"
#include "xfs_errortag.h"
#include "xfs_error.h"
#include "xfs_ag.h"
#include "xfs_buf_mem.h"
struct kmem_cache *xfs_buf_cache;
/*
* Locking orders
*
* xfs_buf_ioacct_inc:
* xfs_buf_ioacct_dec:
* b_sema (caller holds)
* b_lock
*
* xfs_buf_stale:
* b_sema (caller holds)
* b_lock
* lru_lock
*
* xfs_buf_rele:
* b_lock
* pag_buf_lock
* lru_lock
*
* xfs_buftarg_drain_rele
* lru_lock
* b_lock (trylock due to inversion)
*
* xfs_buftarg_isolate
* lru_lock
* b_lock (trylock due to inversion)
*/
static int __xfs_buf_submit(struct xfs_buf *bp, bool wait);
static inline int
xfs_buf_submit(
struct xfs_buf *bp)
{
return __xfs_buf_submit(bp, !(bp->b_flags & XBF_ASYNC));
}
static inline bool xfs_buf_is_uncached(struct xfs_buf *bp)
{
return bp->b_rhash_key == XFS_BUF_DADDR_NULL;
}
static inline int
xfs_buf_is_vmapped(
struct xfs_buf *bp)
{
/*
* Return true if the buffer is vmapped.
*
* b_addr is null if the buffer is not mapped, but the code is clever
* enough to know it doesn't have to map a single page, so the check has
* to be both for b_addr and bp->b_page_count > 1.
*/
return bp->b_addr && bp->b_page_count > 1;
}
static inline int
xfs_buf_vmap_len(
struct xfs_buf *bp)
{
return (bp->b_page_count * PAGE_SIZE);
}
/*
* Bump the I/O in flight count on the buftarg if we haven't yet done so for
* this buffer. The count is incremented once per buffer (per hold cycle)
* because the corresponding decrement is deferred to buffer release. Buffers
* can undergo I/O multiple times in a hold-release cycle and per buffer I/O
* tracking adds unnecessary overhead. This is used for sychronization purposes
* with unmount (see xfs_buftarg_drain()), so all we really need is a count of
* in-flight buffers.
*
* Buffers that are never released (e.g., superblock, iclog buffers) must set
* the XBF_NO_IOACCT flag before I/O submission. Otherwise, the buftarg count
* never reaches zero and unmount hangs indefinitely.
*/
static inline void
xfs_buf_ioacct_inc(
struct xfs_buf *bp)
{
if (bp->b_flags & XBF_NO_IOACCT)
return;
ASSERT(bp->b_flags & XBF_ASYNC);
spin_lock(&bp->b_lock);
if (!(bp->b_state & XFS_BSTATE_IN_FLIGHT)) {
bp->b_state |= XFS_BSTATE_IN_FLIGHT;
percpu_counter_inc(&bp->b_target->bt_io_count);
}
spin_unlock(&bp->b_lock);
}
/*
* Clear the in-flight state on a buffer about to be released to the LRU or
* freed and unaccount from the buftarg.
*/
static inline void
__xfs_buf_ioacct_dec(
struct xfs_buf *bp)
{
lockdep_assert_held(&bp->b_lock);
if (bp->b_state & XFS_BSTATE_IN_FLIGHT) {
bp->b_state &= ~XFS_BSTATE_IN_FLIGHT;
percpu_counter_dec(&bp->b_target->bt_io_count);
}
}
static inline void
xfs_buf_ioacct_dec(
struct xfs_buf *bp)
{
spin_lock(&bp->b_lock);
__xfs_buf_ioacct_dec(bp);
spin_unlock(&bp->b_lock);
}
/*
* When we mark a buffer stale, we remove the buffer from the LRU and clear the
* b_lru_ref count so that the buffer is freed immediately when the buffer
* reference count falls to zero. If the buffer is already on the LRU, we need
* to remove the reference that LRU holds on the buffer.
*
* This prevents build-up of stale buffers on the LRU.
*/
void
xfs_buf_stale(
struct xfs_buf *bp)
{
ASSERT(xfs_buf_islocked(bp));
bp->b_flags |= XBF_STALE;
/*
* Clear the delwri status so that a delwri queue walker will not
* flush this buffer to disk now that it is stale. The delwri queue has
* a reference to the buffer, so this is safe to do.
*/
bp->b_flags &= ~_XBF_DELWRI_Q;
/*
* Once the buffer is marked stale and unlocked, a subsequent lookup
* could reset b_flags. There is no guarantee that the buffer is
* unaccounted (released to LRU) before that occurs. Drop in-flight
* status now to preserve accounting consistency.
*/
spin_lock(&bp->b_lock);
__xfs_buf_ioacct_dec(bp);
atomic_set(&bp->b_lru_ref, 0);
if (!(bp->b_state & XFS_BSTATE_DISPOSE) &&
(list_lru_del_obj(&bp->b_target->bt_lru, &bp->b_lru)))
atomic_dec(&bp->b_hold);
ASSERT(atomic_read(&bp->b_hold) >= 1);
spin_unlock(&bp->b_lock);
}
static int
xfs_buf_get_maps(
struct xfs_buf *bp,
int map_count)
{
ASSERT(bp->b_maps == NULL);
bp->b_map_count = map_count;
if (map_count == 1) {
bp->b_maps = &bp->__b_map;
return 0;
}
bp->b_maps = kzalloc(map_count * sizeof(struct xfs_buf_map),
GFP_KERNEL | __GFP_NOLOCKDEP | __GFP_NOFAIL);
if (!bp->b_maps)
return -ENOMEM;
return 0;
}
/*
* Frees b_pages if it was allocated.
*/
static void
xfs_buf_free_maps(
struct xfs_buf *bp)
{
if (bp->b_maps != &bp->__b_map) {
kfree(bp->b_maps);
bp->b_maps = NULL;
}
}
static int
_xfs_buf_alloc(
struct xfs_buftarg *target,
struct xfs_buf_map *map,
int nmaps,
xfs_buf_flags_t flags,
struct xfs_buf **bpp)
{
struct xfs_buf *bp;
int error;
int i;
*bpp = NULL;
bp = kmem_cache_zalloc(xfs_buf_cache,
GFP_KERNEL | __GFP_NOLOCKDEP | __GFP_NOFAIL);
/*
* We don't want certain flags to appear in b_flags unless they are
* specifically set by later operations on the buffer.
*/
flags &= ~(XBF_UNMAPPED | XBF_TRYLOCK | XBF_ASYNC | XBF_READ_AHEAD);
atomic_set(&bp->b_hold, 1);
atomic_set(&bp->b_lru_ref, 1);
init_completion(&bp->b_iowait);
INIT_LIST_HEAD(&bp->b_lru);
INIT_LIST_HEAD(&bp->b_list);
INIT_LIST_HEAD(&bp->b_li_list);
sema_init(&bp->b_sema, 0); /* held, no waiters */
spin_lock_init(&bp->b_lock);
bp->b_target = target;
bp->b_mount = target->bt_mount;
bp->b_flags = flags;
/*
* Set length and io_length to the same value initially.
* I/O routines should use io_length, which will be the same in
* most cases but may be reset (e.g. XFS recovery).
*/
error = xfs_buf_get_maps(bp, nmaps);
if (error) {
kmem_cache_free(xfs_buf_cache, bp);
return error;
}
bp->b_rhash_key = map[0].bm_bn;
bp->b_length = 0;
for (i = 0; i < nmaps; i++) {
bp->b_maps[i].bm_bn = map[i].bm_bn;
bp->b_maps[i].bm_len = map[i].bm_len;
bp->b_length += map[i].bm_len;
}
atomic_set(&bp->b_pin_count, 0);
init_waitqueue_head(&bp->b_waiters);
XFS_STATS_INC(bp->b_mount, xb_create);
trace_xfs_buf_init(bp, _RET_IP_);
*bpp = bp;
return 0;
}
static void
xfs_buf_free_pages(
struct xfs_buf *bp)
{
uint i;
ASSERT(bp->b_flags & _XBF_PAGES);
if (xfs_buf_is_vmapped(bp))
vm_unmap_ram(bp->b_addr, bp->b_page_count);
for (i = 0; i < bp->b_page_count; i++) {
if (bp->b_pages[i])
__free_page(bp->b_pages[i]);
}
mm_account_reclaimed_pages(bp->b_page_count);
if (bp->b_pages != bp->b_page_array)
kfree(bp->b_pages);
bp->b_pages = NULL;
bp->b_flags &= ~_XBF_PAGES;
}
static void
xfs_buf_free_callback(
struct callback_head *cb)
{
struct xfs_buf *bp = container_of(cb, struct xfs_buf, b_rcu);
xfs_buf_free_maps(bp);
kmem_cache_free(xfs_buf_cache, bp);
}
static void
xfs_buf_free(
struct xfs_buf *bp)
{
trace_xfs_buf_free(bp, _RET_IP_);
ASSERT(list_empty(&bp->b_lru));
if (xfs_buftarg_is_mem(bp->b_target))
xmbuf_unmap_page(bp);
else if (bp->b_flags & _XBF_PAGES)
xfs_buf_free_pages(bp);
else if (bp->b_flags & _XBF_KMEM)
kfree(bp->b_addr);
call_rcu(&bp->b_rcu, xfs_buf_free_callback);
}
static int
xfs_buf_alloc_kmem(
struct xfs_buf *bp,
xfs_buf_flags_t flags)
{
gfp_t gfp_mask = GFP_KERNEL | __GFP_NOLOCKDEP | __GFP_NOFAIL;
size_t size = BBTOB(bp->b_length);
/* Assure zeroed buffer for non-read cases. */
if (!(flags & XBF_READ))
gfp_mask |= __GFP_ZERO;
bp->b_addr = kmalloc(size, gfp_mask);
if (!bp->b_addr)
return -ENOMEM;
if (((unsigned long)(bp->b_addr + size - 1) & PAGE_MASK) !=
((unsigned long)bp->b_addr & PAGE_MASK)) {
/* b_addr spans two pages - use alloc_page instead */
kfree(bp->b_addr);
bp->b_addr = NULL;
return -ENOMEM;
}
bp->b_offset = offset_in_page(bp->b_addr);
bp->b_pages = bp->b_page_array;
bp->b_pages[0] = kmem_to_page(bp->b_addr);
bp->b_page_count = 1;
bp->b_flags |= _XBF_KMEM;
return 0;
}
static int
xfs_buf_alloc_pages(
struct xfs_buf *bp,
xfs_buf_flags_t flags)
{
gfp_t gfp_mask = GFP_KERNEL | __GFP_NOLOCKDEP | __GFP_NOWARN;
long filled = 0;
if (flags & XBF_READ_AHEAD)
gfp_mask |= __GFP_NORETRY;
/* Make sure that we have a page list */
bp->b_page_count = DIV_ROUND_UP(BBTOB(bp->b_length), PAGE_SIZE);
if (bp->b_page_count <= XB_PAGES) {
bp->b_pages = bp->b_page_array;
} else {
bp->b_pages = kzalloc(sizeof(struct page *) * bp->b_page_count,
gfp_mask);
if (!bp->b_pages)
return -ENOMEM;
}
bp->b_flags |= _XBF_PAGES;
/* Assure zeroed buffer for non-read cases. */
if (!(flags & XBF_READ))
gfp_mask |= __GFP_ZERO;
/*
* Bulk filling of pages can take multiple calls. Not filling the entire
* array is not an allocation failure, so don't back off if we get at
* least one extra page.
*/
for (;;) {
long last = filled;
filled = alloc_pages_bulk_array(gfp_mask, bp->b_page_count,
bp->b_pages);
if (filled == bp->b_page_count) {
XFS_STATS_INC(bp->b_mount, xb_page_found);
break;
}
if (filled != last)
continue;
if (flags & XBF_READ_AHEAD) {
xfs_buf_free_pages(bp);
return -ENOMEM;
}
XFS_STATS_INC(bp->b_mount, xb_page_retries);
memalloc_retry_wait(gfp_mask);
}
return 0;
}
/*
* Map buffer into kernel address-space if necessary.
*/
STATIC int
_xfs_buf_map_pages(
struct xfs_buf *bp,
xfs_buf_flags_t flags)
{
ASSERT(bp->b_flags & _XBF_PAGES);
if (bp->b_page_count == 1) {
/* A single page buffer is always mappable */
bp->b_addr = page_address(bp->b_pages[0]);
} else if (flags & XBF_UNMAPPED) {
bp->b_addr = NULL;
} else {
int retried = 0;
unsigned nofs_flag;
/*
* vm_map_ram() will allocate auxiliary structures (e.g.
* pagetables) with GFP_KERNEL, yet we often under a scoped nofs
* context here. Mixing GFP_KERNEL with GFP_NOFS allocations
* from the same call site that can be run from both above and
* below memory reclaim causes lockdep false positives. Hence we
* always need to force this allocation to nofs context because
* we can't pass __GFP_NOLOCKDEP down to auxillary structures to
* prevent false positive lockdep reports.
*
* XXX(dgc): I think dquot reclaim is the only place we can get
* to this function from memory reclaim context now. If we fix
* that like we've fixed inode reclaim to avoid writeback from
* reclaim, this nofs wrapping can go away.
*/
nofs_flag = memalloc_nofs_save();
do {
bp->b_addr = vm_map_ram(bp->b_pages, bp->b_page_count,
-1);
if (bp->b_addr)
break;
vm_unmap_aliases();
} while (retried++ <= 1);
memalloc_nofs_restore(nofs_flag);
if (!bp->b_addr)
return -ENOMEM;
}
return 0;
}
/*
* Finding and Reading Buffers
*/
static int
_xfs_buf_obj_cmp(
struct rhashtable_compare_arg *arg,
const void *obj)
{
const struct xfs_buf_map *map = arg->key;
const struct xfs_buf *bp = obj;
/*
* The key hashing in the lookup path depends on the key being the
* first element of the compare_arg, make sure to assert this.
*/
BUILD_BUG_ON(offsetof(struct xfs_buf_map, bm_bn) != 0);
if (bp->b_rhash_key != map->bm_bn)
return 1;
if (unlikely(bp->b_length != map->bm_len)) {
/*
* found a block number match. If the range doesn't
* match, the only way this is allowed is if the buffer
* in the cache is stale and the transaction that made
* it stale has not yet committed. i.e. we are
* reallocating a busy extent. Skip this buffer and
* continue searching for an exact match.
*
* Note: If we're scanning for incore buffers to stale, don't
* complain if we find non-stale buffers.
*/
if (!(map->bm_flags & XBM_LIVESCAN))
ASSERT(bp->b_flags & XBF_STALE);
return 1;
}
return 0;
}
static const struct rhashtable_params xfs_buf_hash_params = {
.min_size = 32, /* empty AGs have minimal footprint */
.nelem_hint = 16,
.key_len = sizeof(xfs_daddr_t),
.key_offset = offsetof(struct xfs_buf, b_rhash_key),
.head_offset = offsetof(struct xfs_buf, b_rhash_head),
.automatic_shrinking = true,
.obj_cmpfn = _xfs_buf_obj_cmp,
};
int
xfs_buf_cache_init(
struct xfs_buf_cache *bch)
{
spin_lock_init(&bch->bc_lock);
return rhashtable_init(&bch->bc_hash, &xfs_buf_hash_params);
}
void
xfs_buf_cache_destroy(
struct xfs_buf_cache *bch)
{
rhashtable_destroy(&bch->bc_hash);
}
static int
xfs_buf_map_verify(
struct xfs_buftarg *btp,
struct xfs_buf_map *map)
{
xfs_daddr_t eofs;
/* Check for IOs smaller than the sector size / not sector aligned */
ASSERT(!(BBTOB(map->bm_len) < btp->bt_meta_sectorsize));
ASSERT(!(BBTOB(map->bm_bn) & (xfs_off_t)btp->bt_meta_sectormask));
/*
* Corrupted block numbers can get through to here, unfortunately, so we
* have to check that the buffer falls within the filesystem bounds.
*/
eofs = XFS_FSB_TO_BB(btp->bt_mount, btp->bt_mount->m_sb.sb_dblocks);
if (map->bm_bn < 0 || map->bm_bn >= eofs) {
xfs_alert(btp->bt_mount,
"%s: daddr 0x%llx out of range, EOFS 0x%llx",
__func__, map->bm_bn, eofs);
WARN_ON(1);
return -EFSCORRUPTED;
}
return 0;
}
static int
xfs_buf_find_lock(
struct xfs_buf *bp,
xfs_buf_flags_t flags)
{
if (flags & XBF_TRYLOCK) {
if (!xfs_buf_trylock(bp)) {
XFS_STATS_INC(bp->b_mount, xb_busy_locked);
return -EAGAIN;
}
} else {
xfs_buf_lock(bp);
XFS_STATS_INC(bp->b_mount, xb_get_locked_waited);
}
/*
* if the buffer is stale, clear all the external state associated with
* it. We need to keep flags such as how we allocated the buffer memory
* intact here.
*/
if (bp->b_flags & XBF_STALE) {
if (flags & XBF_LIVESCAN) {
xfs_buf_unlock(bp);
return -ENOENT;
}
ASSERT((bp->b_flags & _XBF_DELWRI_Q) == 0);
bp->b_flags &= _XBF_KMEM | _XBF_PAGES;
bp->b_ops = NULL;
}
return 0;
}
static inline int
xfs_buf_lookup(
struct xfs_buf_cache *bch,
struct xfs_buf_map *map,
xfs_buf_flags_t flags,
struct xfs_buf **bpp)
{
struct xfs_buf *bp;
int error;
rcu_read_lock();
bp = rhashtable_lookup(&bch->bc_hash, map, xfs_buf_hash_params);
if (!bp || !atomic_inc_not_zero(&bp->b_hold)) {
rcu_read_unlock();
return -ENOENT;
}
rcu_read_unlock();
error = xfs_buf_find_lock(bp, flags);
if (error) {
xfs_buf_rele(bp);
return error;
}
trace_xfs_buf_find(bp, flags, _RET_IP_);
*bpp = bp;
return 0;
}
/*
* Insert the new_bp into the hash table. This consumes the perag reference
* taken for the lookup regardless of the result of the insert.
*/
static int
xfs_buf_find_insert(
struct xfs_buftarg *btp,
struct xfs_buf_cache *bch,
struct xfs_perag *pag,
struct xfs_buf_map *cmap,
struct xfs_buf_map *map,
int nmaps,
xfs_buf_flags_t flags,
struct xfs_buf **bpp)
{
struct xfs_buf *new_bp;
struct xfs_buf *bp;
int error;
error = _xfs_buf_alloc(btp, map, nmaps, flags, &new_bp);
if (error)
goto out_drop_pag;
if (xfs_buftarg_is_mem(new_bp->b_target)) {
error = xmbuf_map_page(new_bp);
} else if (BBTOB(new_bp->b_length) >= PAGE_SIZE ||
xfs_buf_alloc_kmem(new_bp, flags) < 0) {
/*
* For buffers that fit entirely within a single page, first
* attempt to allocate the memory from the heap to minimise
* memory usage. If we can't get heap memory for these small
* buffers, we fall back to using the page allocator.
*/
error = xfs_buf_alloc_pages(new_bp, flags);
}
if (error)
goto out_free_buf;
spin_lock(&bch->bc_lock);
bp = rhashtable_lookup_get_insert_fast(&bch->bc_hash,
&new_bp->b_rhash_head, xfs_buf_hash_params);
if (IS_ERR(bp)) {
error = PTR_ERR(bp);
spin_unlock(&bch->bc_lock);
goto out_free_buf;
}
if (bp) {
/* found an existing buffer */
atomic_inc(&bp->b_hold);
spin_unlock(&bch->bc_lock);
error = xfs_buf_find_lock(bp, flags);
if (error)
xfs_buf_rele(bp);
else
*bpp = bp;
goto out_free_buf;
}
/* The new buffer keeps the perag reference until it is freed. */
new_bp->b_pag = pag;
spin_unlock(&bch->bc_lock);
*bpp = new_bp;
return 0;
out_free_buf:
xfs_buf_free(new_bp);
out_drop_pag:
if (pag)
xfs_perag_put(pag);
return error;
}
static inline struct xfs_perag *
xfs_buftarg_get_pag(
struct xfs_buftarg *btp,
const struct xfs_buf_map *map)
{
struct xfs_mount *mp = btp->bt_mount;
if (xfs_buftarg_is_mem(btp))
return NULL;
return xfs_perag_get(mp, xfs_daddr_to_agno(mp, map->bm_bn));
}
static inline struct xfs_buf_cache *
xfs_buftarg_buf_cache(
struct xfs_buftarg *btp,
struct xfs_perag *pag)
{
if (pag)
return &pag->pag_bcache;
return btp->bt_cache;
}
/*
* Assembles a buffer covering the specified range. The code is optimised for
* cache hits, as metadata intensive workloads will see 3 orders of magnitude
* more hits than misses.
*/
int
xfs_buf_get_map(
struct xfs_buftarg *btp,
struct xfs_buf_map *map,
int nmaps,
xfs_buf_flags_t flags,
struct xfs_buf **bpp)
{
struct xfs_buf_cache *bch;
struct xfs_perag *pag;
struct xfs_buf *bp = NULL;
struct xfs_buf_map cmap = { .bm_bn = map[0].bm_bn };
int error;
int i;
if (flags & XBF_LIVESCAN)
cmap.bm_flags |= XBM_LIVESCAN;
for (i = 0; i < nmaps; i++)
cmap.bm_len += map[i].bm_len;
error = xfs_buf_map_verify(btp, &cmap);
if (error)
return error;
pag = xfs_buftarg_get_pag(btp, &cmap);
bch = xfs_buftarg_buf_cache(btp, pag);
error = xfs_buf_lookup(bch, &cmap, flags, &bp);
if (error && error != -ENOENT)
goto out_put_perag;
/* cache hits always outnumber misses by at least 10:1 */
if (unlikely(!bp)) {
XFS_STATS_INC(btp->bt_mount, xb_miss_locked);
if (flags & XBF_INCORE)
goto out_put_perag;
/* xfs_buf_find_insert() consumes the perag reference. */
error = xfs_buf_find_insert(btp, bch, pag, &cmap, map, nmaps,
flags, &bp);
if (error)
return error;
} else {
XFS_STATS_INC(btp->bt_mount, xb_get_locked);
if (pag)
xfs_perag_put(pag);
}
/* We do not hold a perag reference anymore. */
if (!bp->b_addr) {
error = _xfs_buf_map_pages(bp, flags);
if (unlikely(error)) {
xfs_warn_ratelimited(btp->bt_mount,
"%s: failed to map %u pages", __func__,
bp->b_page_count);
xfs_buf_relse(bp);
return error;
}
}
/*
* Clear b_error if this is a lookup from a caller that doesn't expect
* valid data to be found in the buffer.
*/
if (!(flags & XBF_READ))
xfs_buf_ioerror(bp, 0);
XFS_STATS_INC(btp->bt_mount, xb_get);
trace_xfs_buf_get(bp, flags, _RET_IP_);
*bpp = bp;
return 0;
out_put_perag:
if (pag)
xfs_perag_put(pag);
return error;
}
int
_xfs_buf_read(
struct xfs_buf *bp,
xfs_buf_flags_t flags)
{
ASSERT(!(flags & XBF_WRITE));
ASSERT(bp->b_maps[0].bm_bn != XFS_BUF_DADDR_NULL);
bp->b_flags &= ~(XBF_WRITE | XBF_ASYNC | XBF_READ_AHEAD | XBF_DONE);
bp->b_flags |= flags & (XBF_READ | XBF_ASYNC | XBF_READ_AHEAD);
return xfs_buf_submit(bp);
}
/*
* Reverify a buffer found in cache without an attached ->b_ops.
*
* If the caller passed an ops structure and the buffer doesn't have ops
* assigned, set the ops and use it to verify the contents. If verification
* fails, clear XBF_DONE. We assume the buffer has no recorded errors and is
* already in XBF_DONE state on entry.
*
* Under normal operations, every in-core buffer is verified on read I/O
* completion. There are two scenarios that can lead to in-core buffers without
* an assigned ->b_ops. The first is during log recovery of buffers on a V4
* filesystem, though these buffers are purged at the end of recovery. The
* other is online repair, which intentionally reads with a NULL buffer ops to
* run several verifiers across an in-core buffer in order to establish buffer
* type. If repair can't establish that, the buffer will be left in memory
* with NULL buffer ops.
*/
int
xfs_buf_reverify(
struct xfs_buf *bp,
const struct xfs_buf_ops *ops)
{
ASSERT(bp->b_flags & XBF_DONE);
ASSERT(bp->b_error == 0);
if (!ops || bp->b_ops)
return 0;
bp->b_ops = ops;
bp->b_ops->verify_read(bp);
if (bp->b_error)
bp->b_flags &= ~XBF_DONE;
return bp->b_error;
}
int
xfs_buf_read_map(
struct xfs_buftarg *target,
struct xfs_buf_map *map,
int nmaps,
xfs_buf_flags_t flags,
struct xfs_buf **bpp,
const struct xfs_buf_ops *ops,
xfs_failaddr_t fa)
{
struct xfs_buf *bp;
int error;
flags |= XBF_READ;
*bpp = NULL;
error = xfs_buf_get_map(target, map, nmaps, flags, &bp);
if (error)
return error;
trace_xfs_buf_read(bp, flags, _RET_IP_);
if (!(bp->b_flags & XBF_DONE)) {
/* Initiate the buffer read and wait. */
XFS_STATS_INC(target->bt_mount, xb_get_read);
bp->b_ops = ops;
error = _xfs_buf_read(bp, flags);
/* Readahead iodone already dropped the buffer, so exit. */
if (flags & XBF_ASYNC)
return 0;
} else {
/* Buffer already read; all we need to do is check it. */
error = xfs_buf_reverify(bp, ops);
/* Readahead already finished; drop the buffer and exit. */
if (flags & XBF_ASYNC) {
xfs_buf_relse(bp);
return 0;
}
/* We do not want read in the flags */
bp->b_flags &= ~XBF_READ;
ASSERT(bp->b_ops != NULL || ops == NULL);
}
/*
* If we've had a read error, then the contents of the buffer are
* invalid and should not be used. To ensure that a followup read tries
* to pull the buffer from disk again, we clear the XBF_DONE flag and
* mark the buffer stale. This ensures that anyone who has a current
* reference to the buffer will interpret it's contents correctly and
* future cache lookups will also treat it as an empty, uninitialised
* buffer.
*/
if (error) {
/*
* Check against log shutdown for error reporting because
* metadata writeback may require a read first and we need to
* report errors in metadata writeback until the log is shut
* down. High level transaction read functions already check
* against mount shutdown, anyway, so we only need to be
* concerned about low level IO interactions here.
*/
if (!xlog_is_shutdown(target->bt_mount->m_log))
xfs_buf_ioerror_alert(bp, fa);
bp->b_flags &= ~XBF_DONE;
xfs_buf_stale(bp);
xfs_buf_relse(bp);
/* bad CRC means corrupted metadata */
if (error == -EFSBADCRC)
error = -EFSCORRUPTED;
return error;
}
*bpp = bp;
return 0;
}
/*
* If we are not low on memory then do the readahead in a deadlock
* safe manner.
*/
void
xfs_buf_readahead_map(
struct xfs_buftarg *target,
struct xfs_buf_map *map,
int nmaps,
const struct xfs_buf_ops *ops)
{
struct xfs_buf *bp;
/*
* Currently we don't have a good means or justification for performing
* xmbuf_map_page asynchronously, so we don't do readahead.
*/
if (xfs_buftarg_is_mem(target))
return;
xfs_buf_read_map(target, map, nmaps,
XBF_TRYLOCK | XBF_ASYNC | XBF_READ_AHEAD, &bp, ops,
__this_address);
}
/*
* Read an uncached buffer from disk. Allocates and returns a locked
* buffer containing the disk contents or nothing. Uncached buffers always have
* a cache index of XFS_BUF_DADDR_NULL so we can easily determine if the buffer
* is cached or uncached during fault diagnosis.
*/
int
xfs_buf_read_uncached(
struct xfs_buftarg *target,
xfs_daddr_t daddr,
size_t numblks,
xfs_buf_flags_t flags,
struct xfs_buf **bpp,
const struct xfs_buf_ops *ops)
{
struct xfs_buf *bp;
int error;
*bpp = NULL;
error = xfs_buf_get_uncached(target, numblks, flags, &bp);
if (error)
return error;
/* set up the buffer for a read IO */
ASSERT(bp->b_map_count == 1);
bp->b_rhash_key = XFS_BUF_DADDR_NULL;
bp->b_maps[0].bm_bn = daddr;
bp->b_flags |= XBF_READ;
bp->b_ops = ops;
xfs_buf_submit(bp);
if (bp->b_error) {
error = bp->b_error;
xfs_buf_relse(bp);
return error;
}
*bpp = bp;
return 0;
}
int
xfs_buf_get_uncached(
struct xfs_buftarg *target,
size_t numblks,
xfs_buf_flags_t flags,
struct xfs_buf **bpp)
{
int error;
struct xfs_buf *bp;
DEFINE_SINGLE_BUF_MAP(map, XFS_BUF_DADDR_NULL, numblks);
*bpp = NULL;
/* flags might contain irrelevant bits, pass only what we care about */
error = _xfs_buf_alloc(target, &map, 1, flags & XBF_NO_IOACCT, &bp);
if (error)
return error;
if (xfs_buftarg_is_mem(bp->b_target))
error = xmbuf_map_page(bp);
else
error = xfs_buf_alloc_pages(bp, flags);
if (error)
goto fail_free_buf;
error = _xfs_buf_map_pages(bp, 0);
if (unlikely(error)) {
xfs_warn(target->bt_mount,
"%s: failed to map pages", __func__);
goto fail_free_buf;
}
trace_xfs_buf_get_uncached(bp, _RET_IP_);
*bpp = bp;
return 0;
fail_free_buf:
xfs_buf_free(bp);
return error;
}
/*
* Increment reference count on buffer, to hold the buffer concurrently
* with another thread which may release (free) the buffer asynchronously.
* Must hold the buffer already to call this function.
*/
void
xfs_buf_hold(
struct xfs_buf *bp)
{
trace_xfs_buf_hold(bp, _RET_IP_);
atomic_inc(&bp->b_hold);
}
static void
xfs_buf_rele_uncached(
struct xfs_buf *bp)
{
ASSERT(list_empty(&bp->b_lru));
if (atomic_dec_and_test(&bp->b_hold)) {
xfs_buf_ioacct_dec(bp);
xfs_buf_free(bp);
}
}
static void
xfs_buf_rele_cached(
struct xfs_buf *bp)
{
struct xfs_buftarg *btp = bp->b_target;
struct xfs_perag *pag = bp->b_pag;
struct xfs_buf_cache *bch = xfs_buftarg_buf_cache(btp, pag);
bool release;
bool freebuf = false;
trace_xfs_buf_rele(bp, _RET_IP_);
ASSERT(atomic_read(&bp->b_hold) > 0);
/*
* We grab the b_lock here first to serialise racing xfs_buf_rele()
* calls. The pag_buf_lock being taken on the last reference only
* serialises against racing lookups in xfs_buf_find(). IOWs, the second
* to last reference we drop here is not serialised against the last
* reference until we take bp->b_lock. Hence if we don't grab b_lock
* first, the last "release" reference can win the race to the lock and
* free the buffer before the second-to-last reference is processed,
* leading to a use-after-free scenario.
*/
spin_lock(&bp->b_lock);
release = atomic_dec_and_lock(&bp->b_hold, &bch->bc_lock);
if (!release) {
/*
* Drop the in-flight state if the buffer is already on the LRU
* and it holds the only reference. This is racy because we
* haven't acquired the pag lock, but the use of _XBF_IN_FLIGHT
* ensures the decrement occurs only once per-buf.
*/
if ((atomic_read(&bp->b_hold) == 1) && !list_empty(&bp->b_lru))
__xfs_buf_ioacct_dec(bp);
goto out_unlock;
}
/* the last reference has been dropped ... */
__xfs_buf_ioacct_dec(bp);
if (!(bp->b_flags & XBF_STALE) && atomic_read(&bp->b_lru_ref)) {
/*
* If the buffer is added to the LRU take a new reference to the
* buffer for the LRU and clear the (now stale) dispose list
* state flag
*/
if (list_lru_add_obj(&btp->bt_lru, &bp->b_lru)) {
bp->b_state &= ~XFS_BSTATE_DISPOSE;
atomic_inc(&bp->b_hold);
}
spin_unlock(&bch->bc_lock);
} else {
/*
* most of the time buffers will already be removed from the
* LRU, so optimise that case by checking for the
* XFS_BSTATE_DISPOSE flag indicating the last list the buffer
* was on was the disposal list
*/
if (!(bp->b_state & XFS_BSTATE_DISPOSE)) {
list_lru_del_obj(&btp->bt_lru, &bp->b_lru);
} else {
ASSERT(list_empty(&bp->b_lru));
}
ASSERT(!(bp->b_flags & _XBF_DELWRI_Q));
rhashtable_remove_fast(&bch->bc_hash, &bp->b_rhash_head,
xfs_buf_hash_params);
spin_unlock(&bch->bc_lock);
if (pag)
xfs_perag_put(pag);
freebuf = true;
}
out_unlock:
spin_unlock(&bp->b_lock);
if (freebuf)
xfs_buf_free(bp);
}
/*
* Release a hold on the specified buffer.
*/
void
xfs_buf_rele(
struct xfs_buf *bp)
{
trace_xfs_buf_rele(bp, _RET_IP_);
if (xfs_buf_is_uncached(bp))
xfs_buf_rele_uncached(bp);
else
xfs_buf_rele_cached(bp);
}
/*
* Lock a buffer object, if it is not already locked.
*
* If we come across a stale, pinned, locked buffer, we know that we are
* being asked to lock a buffer that has been reallocated. Because it is
* pinned, we know that the log has not been pushed to disk and hence it
* will still be locked. Rather than continuing to have trylock attempts
* fail until someone else pushes the log, push it ourselves before
* returning. This means that the xfsaild will not get stuck trying
* to push on stale inode buffers.
*/
int
xfs_buf_trylock(
struct xfs_buf *bp)
{
int locked;
locked = down_trylock(&bp->b_sema) == 0;
if (locked)
trace_xfs_buf_trylock(bp, _RET_IP_);
else
trace_xfs_buf_trylock_fail(bp, _RET_IP_);
return locked;
}
/*
* Lock a buffer object.
*
* If we come across a stale, pinned, locked buffer, we know that we
* are being asked to lock a buffer that has been reallocated. Because
* it is pinned, we know that the log has not been pushed to disk and
* hence it will still be locked. Rather than sleeping until someone
* else pushes the log, push it ourselves before trying to get the lock.
*/
void
xfs_buf_lock(
struct xfs_buf *bp)
{
trace_xfs_buf_lock(bp, _RET_IP_);
if (atomic_read(&bp->b_pin_count) && (bp->b_flags & XBF_STALE))
xfs_log_force(bp->b_mount, 0);
down(&bp->b_sema);
trace_xfs_buf_lock_done(bp, _RET_IP_);
}
void
xfs_buf_unlock(
struct xfs_buf *bp)
{
ASSERT(xfs_buf_islocked(bp));
up(&bp->b_sema);
trace_xfs_buf_unlock(bp, _RET_IP_);
}
STATIC void
xfs_buf_wait_unpin(
struct xfs_buf *bp)
{
DECLARE_WAITQUEUE (wait, current);
if (atomic_read(&bp->b_pin_count) == 0)
return;
add_wait_queue(&bp->b_waiters, &wait);
for (;;) {
set_current_state(TASK_UNINTERRUPTIBLE);
if (atomic_read(&bp->b_pin_count) == 0)
break;
io_schedule();
}
remove_wait_queue(&bp->b_waiters, &wait);
set_current_state(TASK_RUNNING);
}
static void
xfs_buf_ioerror_alert_ratelimited(
struct xfs_buf *bp)
{
static unsigned long lasttime;
static struct xfs_buftarg *lasttarg;
if (bp->b_target != lasttarg ||
time_after(jiffies, (lasttime + 5*HZ))) {
lasttime = jiffies;
xfs_buf_ioerror_alert(bp, __this_address);
}
lasttarg = bp->b_target;
}
/*
* Account for this latest trip around the retry handler, and decide if
* we've failed enough times to constitute a permanent failure.
*/
static bool
xfs_buf_ioerror_permanent(
struct xfs_buf *bp,
struct xfs_error_cfg *cfg)
{
struct xfs_mount *mp = bp->b_mount;
if (cfg->max_retries != XFS_ERR_RETRY_FOREVER &&
++bp->b_retries > cfg->max_retries)
return true;
if (cfg->retry_timeout != XFS_ERR_RETRY_FOREVER &&
time_after(jiffies, cfg->retry_timeout + bp->b_first_retry_time))
return true;
/* At unmount we may treat errors differently */
if (xfs_is_unmounting(mp) && mp->m_fail_unmount)
return true;
return false;
}
/*
* On a sync write or shutdown we just want to stale the buffer and let the
* caller handle the error in bp->b_error appropriately.
*
* If the write was asynchronous then no one will be looking for the error. If
* this is the first failure of this type, clear the error state and write the
* buffer out again. This means we always retry an async write failure at least
* once, but we also need to set the buffer up to behave correctly now for
* repeated failures.
*
* If we get repeated async write failures, then we take action according to the
* error configuration we have been set up to use.
*
* Returns true if this function took care of error handling and the caller must
* not touch the buffer again. Return false if the caller should proceed with
* normal I/O completion handling.
*/
static bool
xfs_buf_ioend_handle_error(
struct xfs_buf *bp)
{
struct xfs_mount *mp = bp->b_mount;
struct xfs_error_cfg *cfg;
/*
* If we've already shutdown the journal because of I/O errors, there's
* no point in giving this a retry.
*/
if (xlog_is_shutdown(mp->m_log))
goto out_stale;
xfs_buf_ioerror_alert_ratelimited(bp);
/*
* We're not going to bother about retrying this during recovery.
* One strike!
*/
if (bp->b_flags & _XBF_LOGRECOVERY) {
xfs_force_shutdown(mp, SHUTDOWN_META_IO_ERROR);
return false;
}
/*
* Synchronous writes will have callers process the error.
*/
if (!(bp->b_flags & XBF_ASYNC))
goto out_stale;
trace_xfs_buf_iodone_async(bp, _RET_IP_);
cfg = xfs_error_get_cfg(mp, XFS_ERR_METADATA, bp->b_error);
if (bp->b_last_error != bp->b_error ||
!(bp->b_flags & (XBF_STALE | XBF_WRITE_FAIL))) {
bp->b_last_error = bp->b_error;
if (cfg->retry_timeout != XFS_ERR_RETRY_FOREVER &&
!bp->b_first_retry_time)
bp->b_first_retry_time = jiffies;
goto resubmit;
}
/*
* Permanent error - we need to trigger a shutdown if we haven't already
* to indicate that inconsistency will result from this action.
*/
if (xfs_buf_ioerror_permanent(bp, cfg)) {
xfs_force_shutdown(mp, SHUTDOWN_META_IO_ERROR);
goto out_stale;
}
/* Still considered a transient error. Caller will schedule retries. */
if (bp->b_flags & _XBF_INODES)
xfs_buf_inode_io_fail(bp);
else if (bp->b_flags & _XBF_DQUOTS)
xfs_buf_dquot_io_fail(bp);
else
ASSERT(list_empty(&bp->b_li_list));
xfs_buf_ioerror(bp, 0);
xfs_buf_relse(bp);
return true;
resubmit:
xfs_buf_ioerror(bp, 0);
bp->b_flags |= (XBF_DONE | XBF_WRITE_FAIL);
xfs_buf_submit(bp);
return true;
out_stale:
xfs_buf_stale(bp);
bp->b_flags |= XBF_DONE;
bp->b_flags &= ~XBF_WRITE;
trace_xfs_buf_error_relse(bp, _RET_IP_);
return false;
}
static void
xfs_buf_ioend(
struct xfs_buf *bp)
{
trace_xfs_buf_iodone(bp, _RET_IP_);
/*
* Pull in IO completion errors now. We are guaranteed to be running
* single threaded, so we don't need the lock to read b_io_error.
*/
if (!bp->b_error && bp->b_io_error)
xfs_buf_ioerror(bp, bp->b_io_error);
if (bp->b_flags & XBF_READ) {
if (!bp->b_error && bp->b_ops)
bp->b_ops->verify_read(bp);
if (!bp->b_error)
bp->b_flags |= XBF_DONE;
} else {
if (!bp->b_error) {
bp->b_flags &= ~XBF_WRITE_FAIL;
bp->b_flags |= XBF_DONE;
}
if (unlikely(bp->b_error) && xfs_buf_ioend_handle_error(bp))
return;
/* clear the retry state */
bp->b_last_error = 0;
bp->b_retries = 0;
bp->b_first_retry_time = 0;
/*
* Note that for things like remote attribute buffers, there may
* not be a buffer log item here, so processing the buffer log
* item must remain optional.
*/
if (bp->b_log_item)
xfs_buf_item_done(bp);
if (bp->b_flags & _XBF_INODES)
xfs_buf_inode_iodone(bp);
else if (bp->b_flags & _XBF_DQUOTS)
xfs_buf_dquot_iodone(bp);
}
bp->b_flags &= ~(XBF_READ | XBF_WRITE | XBF_READ_AHEAD |
_XBF_LOGRECOVERY);
if (bp->b_flags & XBF_ASYNC)
xfs_buf_relse(bp);
else
complete(&bp->b_iowait);
}
static void
xfs_buf_ioend_work(
struct work_struct *work)
{
struct xfs_buf *bp =
container_of(work, struct xfs_buf, b_ioend_work);
xfs_buf_ioend(bp);
}
static void
xfs_buf_ioend_async(
struct xfs_buf *bp)
{
INIT_WORK(&bp->b_ioend_work, xfs_buf_ioend_work);
queue_work(bp->b_mount->m_buf_workqueue, &bp->b_ioend_work);
}
void
__xfs_buf_ioerror(
struct xfs_buf *bp,
int error,
xfs_failaddr_t failaddr)
{
ASSERT(error <= 0 && error >= -1000);
bp->b_error = error;
trace_xfs_buf_ioerror(bp, error, failaddr);
}
void
xfs_buf_ioerror_alert(
struct xfs_buf *bp,
xfs_failaddr_t func)
{
xfs_buf_alert_ratelimited(bp, "XFS: metadata IO error",
"metadata I/O error in \"%pS\" at daddr 0x%llx len %d error %d",
func, (uint64_t)xfs_buf_daddr(bp),
bp->b_length, -bp->b_error);
}
/*
* To simulate an I/O failure, the buffer must be locked and held with at least
* three references. The LRU reference is dropped by the stale call. The buf
* item reference is dropped via ioend processing. The third reference is owned
* by the caller and is dropped on I/O completion if the buffer is XBF_ASYNC.
*/
void
xfs_buf_ioend_fail(
struct xfs_buf *bp)
{
bp->b_flags &= ~XBF_DONE;
xfs_buf_stale(bp);
xfs_buf_ioerror(bp, -EIO);
xfs_buf_ioend(bp);
}
int
xfs_bwrite(
struct xfs_buf *bp)
{
int error;
ASSERT(xfs_buf_islocked(bp));
bp->b_flags |= XBF_WRITE;
bp->b_flags &= ~(XBF_ASYNC | XBF_READ | _XBF_DELWRI_Q |
XBF_DONE);
error = xfs_buf_submit(bp);
if (error)
xfs_force_shutdown(bp->b_mount, SHUTDOWN_META_IO_ERROR);
return error;
}
static void
xfs_buf_bio_end_io(
struct bio *bio)
{
struct xfs_buf *bp = (struct xfs_buf *)bio->bi_private;
if (!bio->bi_status &&
(bp->b_flags & XBF_WRITE) && (bp->b_flags & XBF_ASYNC) &&
XFS_TEST_ERROR(false, bp->b_mount, XFS_ERRTAG_BUF_IOERROR))
bio->bi_status = BLK_STS_IOERR;
/*
* don't overwrite existing errors - otherwise we can lose errors on
* buffers that require multiple bios to complete.
*/
if (bio->bi_status) {
int error = blk_status_to_errno(bio->bi_status);
cmpxchg(&bp->b_io_error, 0, error);
}
if (!bp->b_error && xfs_buf_is_vmapped(bp) && (bp->b_flags & XBF_READ))
invalidate_kernel_vmap_range(bp->b_addr, xfs_buf_vmap_len(bp));
if (atomic_dec_and_test(&bp->b_io_remaining) == 1)
xfs_buf_ioend_async(bp);
bio_put(bio);
}
static void
xfs_buf_ioapply_map(
struct xfs_buf *bp,
int map,
int *buf_offset,
int *count,
blk_opf_t op)
{
int page_index;
unsigned int total_nr_pages = bp->b_page_count;
int nr_pages;
struct bio *bio;
sector_t sector = bp->b_maps[map].bm_bn;
int size;
int offset;
/* skip the pages in the buffer before the start offset */
page_index = 0;
offset = *buf_offset;
while (offset >= PAGE_SIZE) {
page_index++;
offset -= PAGE_SIZE;
}
/*
* Limit the IO size to the length of the current vector, and update the
* remaining IO count for the next time around.
*/
size = min_t(int, BBTOB(bp->b_maps[map].bm_len), *count);
*count -= size;
*buf_offset += size;
next_chunk:
atomic_inc(&bp->b_io_remaining);
nr_pages = bio_max_segs(total_nr_pages);
bio = bio_alloc(bp->b_target->bt_bdev, nr_pages, op, GFP_NOIO);
bio->bi_iter.bi_sector = sector;
bio->bi_end_io = xfs_buf_bio_end_io;
bio->bi_private = bp;
for (; size && nr_pages; nr_pages--, page_index++) {
int rbytes, nbytes = PAGE_SIZE - offset;
if (nbytes > size)
nbytes = size;
rbytes = bio_add_page(bio, bp->b_pages[page_index], nbytes,
offset);
if (rbytes < nbytes)
break;
offset = 0;
sector += BTOBB(nbytes);
size -= nbytes;
total_nr_pages--;
}
if (likely(bio->bi_iter.bi_size)) {
if (xfs_buf_is_vmapped(bp)) {
flush_kernel_vmap_range(bp->b_addr,
xfs_buf_vmap_len(bp));
}
submit_bio(bio);
if (size)
goto next_chunk;
} else {
/*
* This is guaranteed not to be the last io reference count
* because the caller (xfs_buf_submit) holds a count itself.
*/
atomic_dec(&bp->b_io_remaining);
xfs_buf_ioerror(bp, -EIO);
bio_put(bio);
}
}
STATIC void
_xfs_buf_ioapply(
struct xfs_buf *bp)
{
struct blk_plug plug;
blk_opf_t op;
int offset;
int size;
int i;
/*
* Make sure we capture only current IO errors rather than stale errors
* left over from previous use of the buffer (e.g. failed readahead).
*/
bp->b_error = 0;
if (bp->b_flags & XBF_WRITE) {
op = REQ_OP_WRITE;
/*
* Run the write verifier callback function if it exists. If
* this function fails it will mark the buffer with an error and
* the IO should not be dispatched.
*/
if (bp->b_ops) {
bp->b_ops->verify_write(bp);
if (bp->b_error) {
xfs_force_shutdown(bp->b_mount,
SHUTDOWN_CORRUPT_INCORE);
return;
}
} else if (bp->b_rhash_key != XFS_BUF_DADDR_NULL) {
struct xfs_mount *mp = bp->b_mount;
/*
* non-crc filesystems don't attach verifiers during
* log recovery, so don't warn for such filesystems.
*/
if (xfs_has_crc(mp)) {
xfs_warn(mp,
"%s: no buf ops on daddr 0x%llx len %d",
__func__, xfs_buf_daddr(bp),
bp->b_length);
xfs_hex_dump(bp->b_addr,
XFS_CORRUPTION_DUMP_LEN);
dump_stack();
}
}
} else {
op = REQ_OP_READ;
if (bp->b_flags & XBF_READ_AHEAD)
op |= REQ_RAHEAD;
}
/* we only use the buffer cache for meta-data */
op |= REQ_META;
/* in-memory targets are directly mapped, no IO required. */
if (xfs_buftarg_is_mem(bp->b_target)) {
xfs_buf_ioend(bp);
return;
}
/*
* Walk all the vectors issuing IO on them. Set up the initial offset
* into the buffer and the desired IO size before we start -
* _xfs_buf_ioapply_vec() will modify them appropriately for each
* subsequent call.
*/
offset = bp->b_offset;
size = BBTOB(bp->b_length);
blk_start_plug(&plug);
for (i = 0; i < bp->b_map_count; i++) {
xfs_buf_ioapply_map(bp, i, &offset, &size, op);
if (bp->b_error)
break;
if (size <= 0)
break; /* all done */
}
blk_finish_plug(&plug);
}
/*
* Wait for I/O completion of a sync buffer and return the I/O error code.
*/
static int
xfs_buf_iowait(
struct xfs_buf *bp)
{
ASSERT(!(bp->b_flags & XBF_ASYNC));
trace_xfs_buf_iowait(bp, _RET_IP_);
wait_for_completion(&bp->b_iowait);
trace_xfs_buf_iowait_done(bp, _RET_IP_);
return bp->b_error;
}
/*
* Buffer I/O submission path, read or write. Asynchronous submission transfers
* the buffer lock ownership and the current reference to the IO. It is not
* safe to reference the buffer after a call to this function unless the caller
* holds an additional reference itself.
*/
static int
__xfs_buf_submit(
struct xfs_buf *bp,
bool wait)
{
int error = 0;
trace_xfs_buf_submit(bp, _RET_IP_);
ASSERT(!(bp->b_flags & _XBF_DELWRI_Q));
/*
* On log shutdown we stale and complete the buffer immediately. We can
* be called to read the superblock before the log has been set up, so
* be careful checking the log state.
*
* Checking the mount shutdown state here can result in the log tail
* moving inappropriately on disk as the log may not yet be shut down.
* i.e. failing this buffer on mount shutdown can remove it from the AIL
* and move the tail of the log forwards without having written this
* buffer to disk. This corrupts the log tail state in memory, and
* because the log may not be shut down yet, it can then be propagated
* to disk before the log is shutdown. Hence we check log shutdown
* state here rather than mount state to avoid corrupting the log tail
* on shutdown.
*/
if (bp->b_mount->m_log &&
xlog_is_shutdown(bp->b_mount->m_log)) {
xfs_buf_ioend_fail(bp);
return -EIO;
}
/*
* Grab a reference so the buffer does not go away underneath us. For
* async buffers, I/O completion drops the callers reference, which
* could occur before submission returns.
*/
xfs_buf_hold(bp);
if (bp->b_flags & XBF_WRITE)
xfs_buf_wait_unpin(bp);
/* clear the internal error state to avoid spurious errors */
bp->b_io_error = 0;
/*
* Set the count to 1 initially, this will stop an I/O completion
* callout which happens before we have started all the I/O from calling
* xfs_buf_ioend too early.
*/
atomic_set(&bp->b_io_remaining, 1);
if (bp->b_flags & XBF_ASYNC)
xfs_buf_ioacct_inc(bp);
_xfs_buf_ioapply(bp);
/*
* If _xfs_buf_ioapply failed, we can get back here with only the IO
* reference we took above. If we drop it to zero, run completion so
* that we don't return to the caller with completion still pending.
*/
if (atomic_dec_and_test(&bp->b_io_remaining) == 1) {
if (bp->b_error || !(bp->b_flags & XBF_ASYNC))
xfs_buf_ioend(bp);
else
xfs_buf_ioend_async(bp);
}
if (wait)
error = xfs_buf_iowait(bp);
/*
* Release the hold that keeps the buffer referenced for the entire
* I/O. Note that if the buffer is async, it is not safe to reference
* after this release.
*/
xfs_buf_rele(bp);
return error;
}
void *
xfs_buf_offset(
struct xfs_buf *bp,
size_t offset)
{
struct page *page;
if (bp->b_addr)
return bp->b_addr + offset;
page = bp->b_pages[offset >> PAGE_SHIFT];
return page_address(page) + (offset & (PAGE_SIZE-1));
}
void
xfs_buf_zero(
struct xfs_buf *bp,
size_t boff,
size_t bsize)
{
size_t bend;
bend = boff + bsize;
while (boff < bend) {
struct page *page;
int page_index, page_offset, csize;
page_index = (boff + bp->b_offset) >> PAGE_SHIFT;
page_offset = (boff + bp->b_offset) & ~PAGE_MASK;
page = bp->b_pages[page_index];
csize = min_t(size_t, PAGE_SIZE - page_offset,
BBTOB(bp->b_length) - boff);
ASSERT((csize + page_offset) <= PAGE_SIZE);
memset(page_address(page) + page_offset, 0, csize);
boff += csize;
}
}
/*
* Log a message about and stale a buffer that a caller has decided is corrupt.
*
* This function should be called for the kinds of metadata corruption that
* cannot be detect from a verifier, such as incorrect inter-block relationship
* data. Do /not/ call this function from a verifier function.
*
* The buffer must be XBF_DONE prior to the call. Afterwards, the buffer will
* be marked stale, but b_error will not be set. The caller is responsible for
* releasing the buffer or fixing it.
*/
void
__xfs_buf_mark_corrupt(
struct xfs_buf *bp,
xfs_failaddr_t fa)
{
ASSERT(bp->b_flags & XBF_DONE);
xfs_buf_corruption_error(bp, fa);
xfs_buf_stale(bp);
}
/*
* Handling of buffer targets (buftargs).
*/
/*
* Wait for any bufs with callbacks that have been submitted but have not yet
* returned. These buffers will have an elevated hold count, so wait on those
* while freeing all the buffers only held by the LRU.
*/
static enum lru_status
xfs_buftarg_drain_rele(
struct list_head *item,
struct list_lru_one *lru,
spinlock_t *lru_lock,
void *arg)
{
struct xfs_buf *bp = container_of(item, struct xfs_buf, b_lru);
struct list_head *dispose = arg;
if (atomic_read(&bp->b_hold) > 1) {
/* need to wait, so skip it this pass */
trace_xfs_buf_drain_buftarg(bp, _RET_IP_);
return LRU_SKIP;
}
if (!spin_trylock(&bp->b_lock))
return LRU_SKIP;
/*
* clear the LRU reference count so the buffer doesn't get
* ignored in xfs_buf_rele().
*/
atomic_set(&bp->b_lru_ref, 0);
bp->b_state |= XFS_BSTATE_DISPOSE;
list_lru_isolate_move(lru, item, dispose);
spin_unlock(&bp->b_lock);
return LRU_REMOVED;
}
/*
* Wait for outstanding I/O on the buftarg to complete.
*/
void
xfs_buftarg_wait(
struct xfs_buftarg *btp)
{
/*
* First wait on the buftarg I/O count for all in-flight buffers to be
* released. This is critical as new buffers do not make the LRU until
* they are released.
*
* Next, flush the buffer workqueue to ensure all completion processing
* has finished. Just waiting on buffer locks is not sufficient for
* async IO as the reference count held over IO is not released until
* after the buffer lock is dropped. Hence we need to ensure here that
* all reference counts have been dropped before we start walking the
* LRU list.
*/
while (percpu_counter_sum(&btp->bt_io_count))
delay(100);
flush_workqueue(btp->bt_mount->m_buf_workqueue);
}
void
xfs_buftarg_drain(
struct xfs_buftarg *btp)
{
LIST_HEAD(dispose);
int loop = 0;
bool write_fail = false;
xfs_buftarg_wait(btp);
/* loop until there is nothing left on the lru list. */
while (list_lru_count(&btp->bt_lru)) {
list_lru_walk(&btp->bt_lru, xfs_buftarg_drain_rele,
&dispose, LONG_MAX);
while (!list_empty(&dispose)) {
struct xfs_buf *bp;
bp = list_first_entry(&dispose, struct xfs_buf, b_lru);
list_del_init(&bp->b_lru);
if (bp->b_flags & XBF_WRITE_FAIL) {
write_fail = true;
xfs_buf_alert_ratelimited(bp,
"XFS: Corruption Alert",
"Corruption Alert: Buffer at daddr 0x%llx had permanent write failures!",
(long long)xfs_buf_daddr(bp));
}
xfs_buf_rele(bp);
}
if (loop++ != 0)
delay(100);
}
/*
* If one or more failed buffers were freed, that means dirty metadata
* was thrown away. This should only ever happen after I/O completion
* handling has elevated I/O error(s) to permanent failures and shuts
* down the journal.
*/
if (write_fail) {
ASSERT(xlog_is_shutdown(btp->bt_mount->m_log));
xfs_alert(btp->bt_mount,
"Please run xfs_repair to determine the extent of the problem.");
}
}
static enum lru_status
xfs_buftarg_isolate(
struct list_head *item,
struct list_lru_one *lru,
spinlock_t *lru_lock,
void *arg)
{
struct xfs_buf *bp = container_of(item, struct xfs_buf, b_lru);
struct list_head *dispose = arg;
/*
* we are inverting the lru lock/bp->b_lock here, so use a trylock.
* If we fail to get the lock, just skip it.
*/
if (!spin_trylock(&bp->b_lock))
return LRU_SKIP;
/*
* Decrement the b_lru_ref count unless the value is already
* zero. If the value is already zero, we need to reclaim the
* buffer, otherwise it gets another trip through the LRU.
*/
if (atomic_add_unless(&bp->b_lru_ref, -1, 0)) {
spin_unlock(&bp->b_lock);
return LRU_ROTATE;
}
bp->b_state |= XFS_BSTATE_DISPOSE;
list_lru_isolate_move(lru, item, dispose);
spin_unlock(&bp->b_lock);
return LRU_REMOVED;
}
static unsigned long
xfs_buftarg_shrink_scan(
struct shrinker *shrink,
struct shrink_control *sc)
{
struct xfs_buftarg *btp = shrink->private_data;
LIST_HEAD(dispose);
unsigned long freed;
freed = list_lru_shrink_walk(&btp->bt_lru, sc,
xfs_buftarg_isolate, &dispose);
while (!list_empty(&dispose)) {
struct xfs_buf *bp;
bp = list_first_entry(&dispose, struct xfs_buf, b_lru);
list_del_init(&bp->b_lru);
xfs_buf_rele(bp);
}
return freed;
}
static unsigned long
xfs_buftarg_shrink_count(
struct shrinker *shrink,
struct shrink_control *sc)
{
struct xfs_buftarg *btp = shrink->private_data;
return list_lru_shrink_count(&btp->bt_lru, sc);
}
void
xfs_destroy_buftarg(
struct xfs_buftarg *btp)
{
shrinker_free(btp->bt_shrinker);
ASSERT(percpu_counter_sum(&btp->bt_io_count) == 0);
percpu_counter_destroy(&btp->bt_io_count);
list_lru_destroy(&btp->bt_lru);
}
void
xfs_free_buftarg(
struct xfs_buftarg *btp)
{
xfs_destroy_buftarg(btp);
fs_put_dax(btp->bt_daxdev, btp->bt_mount);
/* the main block device is closed by kill_block_super */
if (btp->bt_bdev != btp->bt_mount->m_super->s_bdev)
bdev_fput(btp->bt_bdev_file);
kfree(btp);
}
int
xfs_setsize_buftarg(
struct xfs_buftarg *btp,
unsigned int sectorsize)
{
/* Set up metadata sector size info */
btp->bt_meta_sectorsize = sectorsize;
btp->bt_meta_sectormask = sectorsize - 1;
if (set_blocksize(btp->bt_bdev_file, sectorsize)) {
xfs_warn(btp->bt_mount,
"Cannot set_blocksize to %u on device %pg",
sectorsize, btp->bt_bdev);
return -EINVAL;
}
return 0;
}
int
xfs_init_buftarg(
struct xfs_buftarg *btp,
size_t logical_sectorsize,
const char *descr)
{
/* Set up device logical sector size mask */
btp->bt_logical_sectorsize = logical_sectorsize;
btp->bt_logical_sectormask = logical_sectorsize - 1;
/*
* Buffer IO error rate limiting. Limit it to no more than 10 messages
* per 30 seconds so as to not spam logs too much on repeated errors.
*/
ratelimit_state_init(&btp->bt_ioerror_rl, 30 * HZ,
DEFAULT_RATELIMIT_BURST);
if (list_lru_init(&btp->bt_lru))
return -ENOMEM;
if (percpu_counter_init(&btp->bt_io_count, 0, GFP_KERNEL))
goto out_destroy_lru;
btp->bt_shrinker =
shrinker_alloc(SHRINKER_NUMA_AWARE, "xfs-buf:%s", descr);
if (!btp->bt_shrinker)
goto out_destroy_io_count;
btp->bt_shrinker->count_objects = xfs_buftarg_shrink_count;
btp->bt_shrinker->scan_objects = xfs_buftarg_shrink_scan;
btp->bt_shrinker->private_data = btp;
shrinker_register(btp->bt_shrinker);
return 0;
out_destroy_io_count:
percpu_counter_destroy(&btp->bt_io_count);
out_destroy_lru:
list_lru_destroy(&btp->bt_lru);
return -ENOMEM;
}
struct xfs_buftarg *
xfs_alloc_buftarg(
struct xfs_mount *mp,
struct file *bdev_file)
{
struct xfs_buftarg *btp;
const struct dax_holder_operations *ops = NULL;
#if defined(CONFIG_FS_DAX) && defined(CONFIG_MEMORY_FAILURE)
ops = &xfs_dax_holder_operations;
#endif
btp = kzalloc(sizeof(*btp), GFP_KERNEL | __GFP_NOFAIL);
btp->bt_mount = mp;
btp->bt_bdev_file = bdev_file;
btp->bt_bdev = file_bdev(bdev_file);
btp->bt_dev = btp->bt_bdev->bd_dev;
btp->bt_daxdev = fs_dax_get_by_bdev(btp->bt_bdev, &btp->bt_dax_part_off,
mp, ops);
/*
* When allocating the buftargs we have not yet read the super block and
* thus don't know the file system sector size yet.
*/
if (xfs_setsize_buftarg(btp, bdev_logical_block_size(btp->bt_bdev)))
goto error_free;
if (xfs_init_buftarg(btp, bdev_logical_block_size(btp->bt_bdev),
mp->m_super->s_id))
goto error_free;
return btp;
error_free:
kfree(btp);
return NULL;
}
static inline void
xfs_buf_list_del(
struct xfs_buf *bp)
{
list_del_init(&bp->b_list);
wake_up_var(&bp->b_list);
}
/*
* Cancel a delayed write list.
*
* Remove each buffer from the list, clear the delwri queue flag and drop the
* associated buffer reference.
*/
void
xfs_buf_delwri_cancel(
struct list_head *list)
{
struct xfs_buf *bp;
while (!list_empty(list)) {
bp = list_first_entry(list, struct xfs_buf, b_list);
xfs_buf_lock(bp);
bp->b_flags &= ~_XBF_DELWRI_Q;
xfs_buf_list_del(bp);
xfs_buf_relse(bp);
}
}
/*
* Add a buffer to the delayed write list.
*
* This queues a buffer for writeout if it hasn't already been. Note that
* neither this routine nor the buffer list submission functions perform
* any internal synchronization. It is expected that the lists are thread-local
* to the callers.
*
* Returns true if we queued up the buffer, or false if it already had
* been on the buffer list.
*/
bool
xfs_buf_delwri_queue(
struct xfs_buf *bp,
struct list_head *list)
{
ASSERT(xfs_buf_islocked(bp));
ASSERT(!(bp->b_flags & XBF_READ));
/*
* If the buffer is already marked delwri it already is queued up
* by someone else for imediate writeout. Just ignore it in that
* case.
*/
if (bp->b_flags & _XBF_DELWRI_Q) {
trace_xfs_buf_delwri_queued(bp, _RET_IP_);
return false;
}
trace_xfs_buf_delwri_queue(bp, _RET_IP_);
/*
* If a buffer gets written out synchronously or marked stale while it
* is on a delwri list we lazily remove it. To do this, the other party
* clears the _XBF_DELWRI_Q flag but otherwise leaves the buffer alone.
* It remains referenced and on the list. In a rare corner case it
* might get readded to a delwri list after the synchronous writeout, in
* which case we need just need to re-add the flag here.
*/
bp->b_flags |= _XBF_DELWRI_Q;
if (list_empty(&bp->b_list)) {
atomic_inc(&bp->b_hold);
list_add_tail(&bp->b_list, list);
}
return true;
}
/*
* Queue a buffer to this delwri list as part of a data integrity operation.
* If the buffer is on any other delwri list, we'll wait for that to clear
* so that the caller can submit the buffer for IO and wait for the result.
* Callers must ensure the buffer is not already on the list.
*/
void
xfs_buf_delwri_queue_here(
struct xfs_buf *bp,
struct list_head *buffer_list)
{
/*
* We need this buffer to end up on the /caller's/ delwri list, not any
* old list. This can happen if the buffer is marked stale (which
* clears DELWRI_Q) after the AIL queues the buffer to its list but
* before the AIL has a chance to submit the list.
*/
while (!list_empty(&bp->b_list)) {
xfs_buf_unlock(bp);
wait_var_event(&bp->b_list, list_empty(&bp->b_list));
xfs_buf_lock(bp);
}
ASSERT(!(bp->b_flags & _XBF_DELWRI_Q));
xfs_buf_delwri_queue(bp, buffer_list);
}
/*
* Compare function is more complex than it needs to be because
* the return value is only 32 bits and we are doing comparisons
* on 64 bit values
*/
static int
xfs_buf_cmp(
void *priv,
const struct list_head *a,
const struct list_head *b)
{
struct xfs_buf *ap = container_of(a, struct xfs_buf, b_list);
struct xfs_buf *bp = container_of(b, struct xfs_buf, b_list);
xfs_daddr_t diff;
diff = ap->b_maps[0].bm_bn - bp->b_maps[0].bm_bn;
if (diff < 0)
return -1;
if (diff > 0)
return 1;
return 0;
}
/*
* Submit buffers for write. If wait_list is specified, the buffers are
* submitted using sync I/O and placed on the wait list such that the caller can
* iowait each buffer. Otherwise async I/O is used and the buffers are released
* at I/O completion time. In either case, buffers remain locked until I/O
* completes and the buffer is released from the queue.
*/
static int
xfs_buf_delwri_submit_buffers(
struct list_head *buffer_list,
struct list_head *wait_list)
{
struct xfs_buf *bp, *n;
int pinned = 0;
struct blk_plug plug;
list_sort(NULL, buffer_list, xfs_buf_cmp);
blk_start_plug(&plug);
list_for_each_entry_safe(bp, n, buffer_list, b_list) {
if (!wait_list) {
if (!xfs_buf_trylock(bp))
continue;
if (xfs_buf_ispinned(bp)) {
xfs_buf_unlock(bp);
pinned++;
continue;
}
} else {
xfs_buf_lock(bp);
}
/*
* Someone else might have written the buffer synchronously or
* marked it stale in the meantime. In that case only the
* _XBF_DELWRI_Q flag got cleared, and we have to drop the
* reference and remove it from the list here.
*/
if (!(bp->b_flags & _XBF_DELWRI_Q)) {
xfs_buf_list_del(bp);
xfs_buf_relse(bp);
continue;
}
trace_xfs_buf_delwri_split(bp, _RET_IP_);
/*
* If we have a wait list, each buffer (and associated delwri
* queue reference) transfers to it and is submitted
* synchronously. Otherwise, drop the buffer from the delwri
* queue and submit async.
*/
bp->b_flags &= ~_XBF_DELWRI_Q;
bp->b_flags |= XBF_WRITE;
if (wait_list) {
bp->b_flags &= ~XBF_ASYNC;
list_move_tail(&bp->b_list, wait_list);
} else {
bp->b_flags |= XBF_ASYNC;
xfs_buf_list_del(bp);
}
__xfs_buf_submit(bp, false);
}
blk_finish_plug(&plug);
return pinned;
}
/*
* Write out a buffer list asynchronously.
*
* This will take the @buffer_list, write all non-locked and non-pinned buffers
* out and not wait for I/O completion on any of the buffers. This interface
* is only safely useable for callers that can track I/O completion by higher
* level means, e.g. AIL pushing as the @buffer_list is consumed in this
* function.
*
* Note: this function will skip buffers it would block on, and in doing so
* leaves them on @buffer_list so they can be retried on a later pass. As such,
* it is up to the caller to ensure that the buffer list is fully submitted or
* cancelled appropriately when they are finished with the list. Failure to
* cancel or resubmit the list until it is empty will result in leaked buffers
* at unmount time.
*/
int
xfs_buf_delwri_submit_nowait(
struct list_head *buffer_list)
{
return xfs_buf_delwri_submit_buffers(buffer_list, NULL);
}
/*
* Write out a buffer list synchronously.
*
* This will take the @buffer_list, write all buffers out and wait for I/O
* completion on all of the buffers. @buffer_list is consumed by the function,
* so callers must have some other way of tracking buffers if they require such
* functionality.
*/
int
xfs_buf_delwri_submit(
struct list_head *buffer_list)
{
LIST_HEAD (wait_list);
int error = 0, error2;
struct xfs_buf *bp;
xfs_buf_delwri_submit_buffers(buffer_list, &wait_list);
/* Wait for IO to complete. */
while (!list_empty(&wait_list)) {
bp = list_first_entry(&wait_list, struct xfs_buf, b_list);
xfs_buf_list_del(bp);
/*
* Wait on the locked buffer, check for errors and unlock and
* release the delwri queue reference.
*/
error2 = xfs_buf_iowait(bp);
xfs_buf_relse(bp);
if (!error)
error = error2;
}
return error;
}
/*
* Push a single buffer on a delwri queue.
*
* The purpose of this function is to submit a single buffer of a delwri queue
* and return with the buffer still on the original queue. The waiting delwri
* buffer submission infrastructure guarantees transfer of the delwri queue
* buffer reference to a temporary wait list. We reuse this infrastructure to
* transfer the buffer back to the original queue.
*
* Note the buffer transitions from the queued state, to the submitted and wait
* listed state and back to the queued state during this call. The buffer
* locking and queue management logic between _delwri_pushbuf() and
* _delwri_queue() guarantee that the buffer cannot be queued to another list
* before returning.
*/
int
xfs_buf_delwri_pushbuf(
struct xfs_buf *bp,
struct list_head *buffer_list)
{
LIST_HEAD (submit_list);
int error;
ASSERT(bp->b_flags & _XBF_DELWRI_Q);
trace_xfs_buf_delwri_pushbuf(bp, _RET_IP_);
/*
* Isolate the buffer to a new local list so we can submit it for I/O
* independently from the rest of the original list.
*/
xfs_buf_lock(bp);
list_move(&bp->b_list, &submit_list);
xfs_buf_unlock(bp);
/*
* Delwri submission clears the DELWRI_Q buffer flag and returns with
* the buffer on the wait list with the original reference. Rather than
* bounce the buffer from a local wait list back to the original list
* after I/O completion, reuse the original list as the wait list.
*/
xfs_buf_delwri_submit_buffers(&submit_list, buffer_list);
/*
* The buffer is now locked, under I/O and wait listed on the original
* delwri queue. Wait for I/O completion, restore the DELWRI_Q flag and
* return with the buffer unlocked and on the original queue.
*/
error = xfs_buf_iowait(bp);
bp->b_flags |= _XBF_DELWRI_Q;
xfs_buf_unlock(bp);
return error;
}
void xfs_buf_set_ref(struct xfs_buf *bp, int lru_ref)
{
/*
* Set the lru reference count to 0 based on the error injection tag.
* This allows userspace to disrupt buffer caching for debug/testing
* purposes.
*/
if (XFS_TEST_ERROR(false, bp->b_mount, XFS_ERRTAG_BUF_LRU_REF))
lru_ref = 0;
atomic_set(&bp->b_lru_ref, lru_ref);
}
/*
* Verify an on-disk magic value against the magic value specified in the
* verifier structure. The verifier magic is in disk byte order so the caller is
* expected to pass the value directly from disk.
*/
bool
xfs_verify_magic(
struct xfs_buf *bp,
__be32 dmagic)
{
struct xfs_mount *mp = bp->b_mount;
int idx;
idx = xfs_has_crc(mp);
if (WARN_ON(!bp->b_ops || !bp->b_ops->magic[idx]))
return false;
return dmagic == bp->b_ops->magic[idx];
}
/*
* Verify an on-disk magic value against the magic value specified in the
* verifier structure. The verifier magic is in disk byte order so the caller is
* expected to pass the value directly from disk.
*/
bool
xfs_verify_magic16(
struct xfs_buf *bp,
__be16 dmagic)
{
struct xfs_mount *mp = bp->b_mount;
int idx;
idx = xfs_has_crc(mp);
if (WARN_ON(!bp->b_ops || !bp->b_ops->magic16[idx]))
return false;
return dmagic == bp->b_ops->magic16[idx];
}
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