v4.19.13 snapshot.
diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
new file mode 100644
index 0000000..e839907
--- /dev/null
+++ b/fs/xfs/xfs_buf.c
@@ -0,0 +1,2124 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2000-2006 Silicon Graphics, Inc.
+ * All Rights Reserved.
+ */
+#include "xfs.h"
+#include <linux/stddef.h>
+#include <linux/errno.h>
+#include <linux/gfp.h>
+#include <linux/pagemap.h>
+#include <linux/init.h>
+#include <linux/vmalloc.h>
+#include <linux/bio.h>
+#include <linux/sysctl.h>
+#include <linux/proc_fs.h>
+#include <linux/workqueue.h>
+#include <linux/percpu.h>
+#include <linux/blkdev.h>
+#include <linux/hash.h>
+#include <linux/kthread.h>
+#include <linux/migrate.h>
+#include <linux/backing-dev.h>
+#include <linux/freezer.h>
+
+#include "xfs_format.h"
+#include "xfs_log_format.h"
+#include "xfs_trans_resv.h"
+#include "xfs_sb.h"
+#include "xfs_mount.h"
+#include "xfs_trace.h"
+#include "xfs_log.h"
+#include "xfs_errortag.h"
+#include "xfs_error.h"
+
+static kmem_zone_t *xfs_buf_zone;
+
+#define xb_to_gfp(flags) \
+ ((((flags) & XBF_READ_AHEAD) ? __GFP_NORETRY : GFP_NOFS) | __GFP_NOWARN)
+
+
+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) - bp->b_offset;
+}
+
+/*
+ * 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_wait_buftarg()), 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(&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 = kmem_zalloc(map_count * sizeof(struct xfs_buf_map),
+ KM_NOFS);
+ 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) {
+ kmem_free(bp->b_maps);
+ bp->b_maps = NULL;
+ }
+}
+
+struct xfs_buf *
+_xfs_buf_alloc(
+ struct xfs_buftarg *target,
+ struct xfs_buf_map *map,
+ int nmaps,
+ xfs_buf_flags_t flags)
+{
+ struct xfs_buf *bp;
+ int error;
+ int i;
+
+ bp = kmem_zone_zalloc(xfs_buf_zone, KM_NOFS);
+ if (unlikely(!bp))
+ return NULL;
+
+ /*
+ * 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_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_zone_free(xfs_buf_zone, bp);
+ return NULL;
+ }
+
+ bp->b_bn = 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;
+ }
+ bp->b_io_length = bp->b_length;
+
+ atomic_set(&bp->b_pin_count, 0);
+ init_waitqueue_head(&bp->b_waiters);
+
+ XFS_STATS_INC(target->bt_mount, xb_create);
+ trace_xfs_buf_init(bp, _RET_IP_);
+
+ return bp;
+}
+
+/*
+ * Allocate a page array capable of holding a specified number
+ * of pages, and point the page buf at it.
+ */
+STATIC int
+_xfs_buf_get_pages(
+ xfs_buf_t *bp,
+ int page_count)
+{
+ /* Make sure that we have a page list */
+ if (bp->b_pages == NULL) {
+ bp->b_page_count = page_count;
+ if (page_count <= XB_PAGES) {
+ bp->b_pages = bp->b_page_array;
+ } else {
+ bp->b_pages = kmem_alloc(sizeof(struct page *) *
+ page_count, KM_NOFS);
+ if (bp->b_pages == NULL)
+ return -ENOMEM;
+ }
+ memset(bp->b_pages, 0, sizeof(struct page *) * page_count);
+ }
+ return 0;
+}
+
+/*
+ * Frees b_pages if it was allocated.
+ */
+STATIC void
+_xfs_buf_free_pages(
+ xfs_buf_t *bp)
+{
+ if (bp->b_pages != bp->b_page_array) {
+ kmem_free(bp->b_pages);
+ bp->b_pages = NULL;
+ }
+}
+
+/*
+ * Releases the specified buffer.
+ *
+ * The modification state of any associated pages is left unchanged.
+ * The buffer must not be on any hash - use xfs_buf_rele instead for
+ * hashed and refcounted buffers
+ */
+void
+xfs_buf_free(
+ xfs_buf_t *bp)
+{
+ trace_xfs_buf_free(bp, _RET_IP_);
+
+ ASSERT(list_empty(&bp->b_lru));
+
+ if (bp->b_flags & _XBF_PAGES) {
+ uint i;
+
+ if (xfs_buf_is_vmapped(bp))
+ vm_unmap_ram(bp->b_addr - bp->b_offset,
+ bp->b_page_count);
+
+ for (i = 0; i < bp->b_page_count; i++) {
+ struct page *page = bp->b_pages[i];
+
+ __free_page(page);
+ }
+ } else if (bp->b_flags & _XBF_KMEM)
+ kmem_free(bp->b_addr);
+ _xfs_buf_free_pages(bp);
+ xfs_buf_free_maps(bp);
+ kmem_zone_free(xfs_buf_zone, bp);
+}
+
+/*
+ * Allocates all the pages for buffer in question and builds it's page list.
+ */
+STATIC int
+xfs_buf_allocate_memory(
+ xfs_buf_t *bp,
+ uint flags)
+{
+ size_t size;
+ size_t nbytes, offset;
+ gfp_t gfp_mask = xb_to_gfp(flags);
+ unsigned short page_count, i;
+ xfs_off_t start, end;
+ int error;
+
+ /*
+ * for buffers that are contained within a single page, just allocate
+ * the memory from the heap - there's no need for the complexity of
+ * page arrays to keep allocation down to order 0.
+ */
+ size = BBTOB(bp->b_length);
+ if (size < PAGE_SIZE) {
+ bp->b_addr = kmem_alloc(size, KM_NOFS);
+ if (!bp->b_addr) {
+ /* low memory - use alloc_page loop instead */
+ goto use_alloc_page;
+ }
+
+ 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 */
+ kmem_free(bp->b_addr);
+ bp->b_addr = NULL;
+ goto use_alloc_page;
+ }
+ bp->b_offset = offset_in_page(bp->b_addr);
+ bp->b_pages = bp->b_page_array;
+ bp->b_pages[0] = virt_to_page(bp->b_addr);
+ bp->b_page_count = 1;
+ bp->b_flags |= _XBF_KMEM;
+ return 0;
+ }
+
+use_alloc_page:
+ start = BBTOB(bp->b_maps[0].bm_bn) >> PAGE_SHIFT;
+ end = (BBTOB(bp->b_maps[0].bm_bn + bp->b_length) + PAGE_SIZE - 1)
+ >> PAGE_SHIFT;
+ page_count = end - start;
+ error = _xfs_buf_get_pages(bp, page_count);
+ if (unlikely(error))
+ return error;
+
+ offset = bp->b_offset;
+ bp->b_flags |= _XBF_PAGES;
+
+ for (i = 0; i < bp->b_page_count; i++) {
+ struct page *page;
+ uint retries = 0;
+retry:
+ page = alloc_page(gfp_mask);
+ if (unlikely(page == NULL)) {
+ if (flags & XBF_READ_AHEAD) {
+ bp->b_page_count = i;
+ error = -ENOMEM;
+ goto out_free_pages;
+ }
+
+ /*
+ * This could deadlock.
+ *
+ * But until all the XFS lowlevel code is revamped to
+ * handle buffer allocation failures we can't do much.
+ */
+ if (!(++retries % 100))
+ xfs_err(NULL,
+ "%s(%u) possible memory allocation deadlock in %s (mode:0x%x)",
+ current->comm, current->pid,
+ __func__, gfp_mask);
+
+ XFS_STATS_INC(bp->b_target->bt_mount, xb_page_retries);
+ congestion_wait(BLK_RW_ASYNC, HZ/50);
+ goto retry;
+ }
+
+ XFS_STATS_INC(bp->b_target->bt_mount, xb_page_found);
+
+ nbytes = min_t(size_t, size, PAGE_SIZE - offset);
+ size -= nbytes;
+ bp->b_pages[i] = page;
+ offset = 0;
+ }
+ return 0;
+
+out_free_pages:
+ for (i = 0; i < bp->b_page_count; i++)
+ __free_page(bp->b_pages[i]);
+ bp->b_flags &= ~_XBF_PAGES;
+ return error;
+}
+
+/*
+ * Map buffer into kernel address-space if necessary.
+ */
+STATIC int
+_xfs_buf_map_pages(
+ xfs_buf_t *bp,
+ uint 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]) + bp->b_offset;
+ } else if (flags & XBF_UNMAPPED) {
+ bp->b_addr = NULL;
+ } else {
+ int retried = 0;
+ unsigned nofs_flag;
+
+ /*
+ * vm_map_ram() will allocate auxillary structures (e.g.
+ * pagetables) with GFP_KERNEL, yet we are likely to be under
+ * GFP_NOFS context here. Hence we need to tell memory reclaim
+ * that we are in such a context via PF_MEMALLOC_NOFS to prevent
+ * memory reclaim re-entering the filesystem here and
+ * potentially deadlocking.
+ */
+ nofs_flag = memalloc_nofs_save();
+ do {
+ bp->b_addr = vm_map_ram(bp->b_pages, bp->b_page_count,
+ -1, PAGE_KERNEL);
+ if (bp->b_addr)
+ break;
+ vm_unmap_aliases();
+ } while (retried++ <= 1);
+ memalloc_nofs_restore(nofs_flag);
+
+ if (!bp->b_addr)
+ return -ENOMEM;
+ bp->b_addr += bp->b_offset;
+ }
+
+ 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_bn != 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.
+ */
+ 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_bn),
+ .head_offset = offsetof(struct xfs_buf, b_rhash_head),
+ .automatic_shrinking = true,
+ .obj_cmpfn = _xfs_buf_obj_cmp,
+};
+
+int
+xfs_buf_hash_init(
+ struct xfs_perag *pag)
+{
+ spin_lock_init(&pag->pag_buf_lock);
+ return rhashtable_init(&pag->pag_buf_hash, &xfs_buf_hash_params);
+}
+
+void
+xfs_buf_hash_destroy(
+ struct xfs_perag *pag)
+{
+ rhashtable_destroy(&pag->pag_buf_hash);
+}
+
+/*
+ * Look up a buffer in the buffer cache and return it referenced and locked
+ * in @found_bp.
+ *
+ * If @new_bp is supplied and we have a lookup miss, insert @new_bp into the
+ * cache.
+ *
+ * If XBF_TRYLOCK is set in @flags, only try to lock the buffer and return
+ * -EAGAIN if we fail to lock it.
+ *
+ * Return values are:
+ * -EFSCORRUPTED if have been supplied with an invalid address
+ * -EAGAIN on trylock failure
+ * -ENOENT if we fail to find a match and @new_bp was NULL
+ * 0, with @found_bp:
+ * - @new_bp if we inserted it into the cache
+ * - the buffer we found and locked.
+ */
+static int
+xfs_buf_find(
+ struct xfs_buftarg *btp,
+ struct xfs_buf_map *map,
+ int nmaps,
+ xfs_buf_flags_t flags,
+ struct xfs_buf *new_bp,
+ struct xfs_buf **found_bp)
+{
+ struct xfs_perag *pag;
+ xfs_buf_t *bp;
+ struct xfs_buf_map cmap = { .bm_bn = map[0].bm_bn };
+ xfs_daddr_t eofs;
+ int i;
+
+ *found_bp = NULL;
+
+ for (i = 0; i < nmaps; i++)
+ cmap.bm_len += map[i].bm_len;
+
+ /* Check for IOs smaller than the sector size / not sector aligned */
+ ASSERT(!(BBTOB(cmap.bm_len) < btp->bt_meta_sectorsize));
+ ASSERT(!(BBTOB(cmap.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 (cmap.bm_bn < 0 || cmap.bm_bn >= eofs) {
+ xfs_alert(btp->bt_mount,
+ "%s: daddr 0x%llx out of range, EOFS 0x%llx",
+ __func__, cmap.bm_bn, eofs);
+ WARN_ON(1);
+ return -EFSCORRUPTED;
+ }
+
+ pag = xfs_perag_get(btp->bt_mount,
+ xfs_daddr_to_agno(btp->bt_mount, cmap.bm_bn));
+
+ spin_lock(&pag->pag_buf_lock);
+ bp = rhashtable_lookup_fast(&pag->pag_buf_hash, &cmap,
+ xfs_buf_hash_params);
+ if (bp) {
+ atomic_inc(&bp->b_hold);
+ goto found;
+ }
+
+ /* No match found */
+ if (!new_bp) {
+ XFS_STATS_INC(btp->bt_mount, xb_miss_locked);
+ spin_unlock(&pag->pag_buf_lock);
+ xfs_perag_put(pag);
+ return -ENOENT;
+ }
+
+ /* the buffer keeps the perag reference until it is freed */
+ new_bp->b_pag = pag;
+ rhashtable_insert_fast(&pag->pag_buf_hash, &new_bp->b_rhash_head,
+ xfs_buf_hash_params);
+ spin_unlock(&pag->pag_buf_lock);
+ *found_bp = new_bp;
+ return 0;
+
+found:
+ spin_unlock(&pag->pag_buf_lock);
+ xfs_perag_put(pag);
+
+ if (!xfs_buf_trylock(bp)) {
+ if (flags & XBF_TRYLOCK) {
+ xfs_buf_rele(bp);
+ XFS_STATS_INC(btp->bt_mount, xb_busy_locked);
+ return -EAGAIN;
+ }
+ xfs_buf_lock(bp);
+ XFS_STATS_INC(btp->bt_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) {
+ ASSERT((bp->b_flags & _XBF_DELWRI_Q) == 0);
+ ASSERT(bp->b_iodone == NULL);
+ bp->b_flags &= _XBF_KMEM | _XBF_PAGES;
+ bp->b_ops = NULL;
+ }
+
+ trace_xfs_buf_find(bp, flags, _RET_IP_);
+ XFS_STATS_INC(btp->bt_mount, xb_get_locked);
+ *found_bp = bp;
+ return 0;
+}
+
+struct xfs_buf *
+xfs_buf_incore(
+ struct xfs_buftarg *target,
+ xfs_daddr_t blkno,
+ size_t numblks,
+ xfs_buf_flags_t flags)
+{
+ struct xfs_buf *bp;
+ int error;
+ DEFINE_SINGLE_BUF_MAP(map, blkno, numblks);
+
+ error = xfs_buf_find(target, &map, 1, flags, NULL, &bp);
+ if (error)
+ return NULL;
+ return bp;
+}
+
+/*
+ * 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.
+ */
+struct xfs_buf *
+xfs_buf_get_map(
+ struct xfs_buftarg *target,
+ struct xfs_buf_map *map,
+ int nmaps,
+ xfs_buf_flags_t flags)
+{
+ struct xfs_buf *bp;
+ struct xfs_buf *new_bp;
+ int error = 0;
+
+ error = xfs_buf_find(target, map, nmaps, flags, NULL, &bp);
+
+ switch (error) {
+ case 0:
+ /* cache hit */
+ goto found;
+ case -EAGAIN:
+ /* cache hit, trylock failure, caller handles failure */
+ ASSERT(flags & XBF_TRYLOCK);
+ return NULL;
+ case -ENOENT:
+ /* cache miss, go for insert */
+ break;
+ case -EFSCORRUPTED:
+ default:
+ /*
+ * None of the higher layers understand failure types
+ * yet, so return NULL to signal a fatal lookup error.
+ */
+ return NULL;
+ }
+
+ new_bp = _xfs_buf_alloc(target, map, nmaps, flags);
+ if (unlikely(!new_bp))
+ return NULL;
+
+ error = xfs_buf_allocate_memory(new_bp, flags);
+ if (error) {
+ xfs_buf_free(new_bp);
+ return NULL;
+ }
+
+ error = xfs_buf_find(target, map, nmaps, flags, new_bp, &bp);
+ if (error) {
+ xfs_buf_free(new_bp);
+ return NULL;
+ }
+
+ if (bp != new_bp)
+ xfs_buf_free(new_bp);
+
+found:
+ if (!bp->b_addr) {
+ error = _xfs_buf_map_pages(bp, flags);
+ if (unlikely(error)) {
+ xfs_warn(target->bt_mount,
+ "%s: failed to map pagesn", __func__);
+ xfs_buf_relse(bp);
+ return NULL;
+ }
+ }
+
+ /*
+ * 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(target->bt_mount, xb_get);
+ trace_xfs_buf_get(bp, flags, _RET_IP_);
+ return bp;
+}
+
+STATIC int
+_xfs_buf_read(
+ xfs_buf_t *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);
+ bp->b_flags |= flags & (XBF_READ | XBF_ASYNC | XBF_READ_AHEAD);
+
+ return xfs_buf_submit(bp);
+}
+
+xfs_buf_t *
+xfs_buf_read_map(
+ struct xfs_buftarg *target,
+ struct xfs_buf_map *map,
+ int nmaps,
+ xfs_buf_flags_t flags,
+ const struct xfs_buf_ops *ops)
+{
+ struct xfs_buf *bp;
+
+ flags |= XBF_READ;
+
+ bp = xfs_buf_get_map(target, map, nmaps, flags);
+ if (bp) {
+ trace_xfs_buf_read(bp, flags, _RET_IP_);
+
+ if (!(bp->b_flags & XBF_DONE)) {
+ XFS_STATS_INC(target->bt_mount, xb_get_read);
+ bp->b_ops = ops;
+ _xfs_buf_read(bp, flags);
+ } else if (flags & XBF_ASYNC) {
+ /*
+ * Read ahead call which is already satisfied,
+ * drop the buffer
+ */
+ xfs_buf_relse(bp);
+ return NULL;
+ } else {
+ /* We do not want read in the flags */
+ bp->b_flags &= ~XBF_READ;
+ }
+ }
+
+ return bp;
+}
+
+/*
+ * 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)
+{
+ if (bdi_read_congested(target->bt_bdev->bd_bdi))
+ return;
+
+ xfs_buf_read_map(target, map, nmaps,
+ XBF_TRYLOCK|XBF_ASYNC|XBF_READ_AHEAD, ops);
+}
+
+/*
+ * Read an uncached buffer from disk. Allocates and returns a locked
+ * buffer containing the disk contents or nothing.
+ */
+int
+xfs_buf_read_uncached(
+ struct xfs_buftarg *target,
+ xfs_daddr_t daddr,
+ size_t numblks,
+ int flags,
+ struct xfs_buf **bpp,
+ const struct xfs_buf_ops *ops)
+{
+ struct xfs_buf *bp;
+
+ *bpp = NULL;
+
+ bp = xfs_buf_get_uncached(target, numblks, flags);
+ if (!bp)
+ return -ENOMEM;
+
+ /* set up the buffer for a read IO */
+ ASSERT(bp->b_map_count == 1);
+ bp->b_bn = XFS_BUF_DADDR_NULL; /* always null for uncached buffers */
+ bp->b_maps[0].bm_bn = daddr;
+ bp->b_flags |= XBF_READ;
+ bp->b_ops = ops;
+
+ xfs_buf_submit(bp);
+ if (bp->b_error) {
+ int error = bp->b_error;
+ xfs_buf_relse(bp);
+ return error;
+ }
+
+ *bpp = bp;
+ return 0;
+}
+
+/*
+ * Return a buffer allocated as an empty buffer and associated to external
+ * memory via xfs_buf_associate_memory() back to it's empty state.
+ */
+void
+xfs_buf_set_empty(
+ struct xfs_buf *bp,
+ size_t numblks)
+{
+ if (bp->b_pages)
+ _xfs_buf_free_pages(bp);
+
+ bp->b_pages = NULL;
+ bp->b_page_count = 0;
+ bp->b_addr = NULL;
+ bp->b_length = numblks;
+ bp->b_io_length = numblks;
+
+ ASSERT(bp->b_map_count == 1);
+ bp->b_bn = XFS_BUF_DADDR_NULL;
+ bp->b_maps[0].bm_bn = XFS_BUF_DADDR_NULL;
+ bp->b_maps[0].bm_len = bp->b_length;
+}
+
+static inline struct page *
+mem_to_page(
+ void *addr)
+{
+ if ((!is_vmalloc_addr(addr))) {
+ return virt_to_page(addr);
+ } else {
+ return vmalloc_to_page(addr);
+ }
+}
+
+int
+xfs_buf_associate_memory(
+ xfs_buf_t *bp,
+ void *mem,
+ size_t len)
+{
+ int rval;
+ int i = 0;
+ unsigned long pageaddr;
+ unsigned long offset;
+ size_t buflen;
+ int page_count;
+
+ pageaddr = (unsigned long)mem & PAGE_MASK;
+ offset = (unsigned long)mem - pageaddr;
+ buflen = PAGE_ALIGN(len + offset);
+ page_count = buflen >> PAGE_SHIFT;
+
+ /* Free any previous set of page pointers */
+ if (bp->b_pages)
+ _xfs_buf_free_pages(bp);
+
+ bp->b_pages = NULL;
+ bp->b_addr = mem;
+
+ rval = _xfs_buf_get_pages(bp, page_count);
+ if (rval)
+ return rval;
+
+ bp->b_offset = offset;
+
+ for (i = 0; i < bp->b_page_count; i++) {
+ bp->b_pages[i] = mem_to_page((void *)pageaddr);
+ pageaddr += PAGE_SIZE;
+ }
+
+ bp->b_io_length = BTOBB(len);
+ bp->b_length = BTOBB(buflen);
+
+ return 0;
+}
+
+xfs_buf_t *
+xfs_buf_get_uncached(
+ struct xfs_buftarg *target,
+ size_t numblks,
+ int flags)
+{
+ unsigned long page_count;
+ int error, i;
+ struct xfs_buf *bp;
+ DEFINE_SINGLE_BUF_MAP(map, XFS_BUF_DADDR_NULL, numblks);
+
+ /* flags might contain irrelevant bits, pass only what we care about */
+ bp = _xfs_buf_alloc(target, &map, 1, flags & XBF_NO_IOACCT);
+ if (unlikely(bp == NULL))
+ goto fail;
+
+ page_count = PAGE_ALIGN(numblks << BBSHIFT) >> PAGE_SHIFT;
+ error = _xfs_buf_get_pages(bp, page_count);
+ if (error)
+ goto fail_free_buf;
+
+ for (i = 0; i < page_count; i++) {
+ bp->b_pages[i] = alloc_page(xb_to_gfp(flags));
+ if (!bp->b_pages[i])
+ goto fail_free_mem;
+ }
+ bp->b_flags |= _XBF_PAGES;
+
+ error = _xfs_buf_map_pages(bp, 0);
+ if (unlikely(error)) {
+ xfs_warn(target->bt_mount,
+ "%s: failed to map pages", __func__);
+ goto fail_free_mem;
+ }
+
+ trace_xfs_buf_get_uncached(bp, _RET_IP_);
+ return bp;
+
+ fail_free_mem:
+ while (--i >= 0)
+ __free_page(bp->b_pages[i]);
+ _xfs_buf_free_pages(bp);
+ fail_free_buf:
+ xfs_buf_free_maps(bp);
+ kmem_zone_free(xfs_buf_zone, bp);
+ fail:
+ return NULL;
+}
+
+/*
+ * 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(
+ xfs_buf_t *bp)
+{
+ trace_xfs_buf_hold(bp, _RET_IP_);
+ atomic_inc(&bp->b_hold);
+}
+
+/*
+ * Release a hold on the specified buffer. If the hold count is 1, the buffer is
+ * placed on LRU or freed (depending on b_lru_ref).
+ */
+void
+xfs_buf_rele(
+ xfs_buf_t *bp)
+{
+ struct xfs_perag *pag = bp->b_pag;
+ bool release;
+ bool freebuf = false;
+
+ trace_xfs_buf_rele(bp, _RET_IP_);
+
+ if (!pag) {
+ ASSERT(list_empty(&bp->b_lru));
+ if (atomic_dec_and_test(&bp->b_hold)) {
+ xfs_buf_ioacct_dec(bp);
+ xfs_buf_free(bp);
+ }
+ return;
+ }
+
+ ASSERT(atomic_read(&bp->b_hold) > 0);
+
+ release = atomic_dec_and_lock(&bp->b_hold, &pag->pag_buf_lock);
+ spin_lock(&bp->b_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(&bp->b_target->bt_lru, &bp->b_lru)) {
+ bp->b_state &= ~XFS_BSTATE_DISPOSE;
+ atomic_inc(&bp->b_hold);
+ }
+ spin_unlock(&pag->pag_buf_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(&bp->b_target->bt_lru, &bp->b_lru);
+ } else {
+ ASSERT(list_empty(&bp->b_lru));
+ }
+
+ ASSERT(!(bp->b_flags & _XBF_DELWRI_Q));
+ rhashtable_remove_fast(&pag->pag_buf_hash, &bp->b_rhash_head,
+ xfs_buf_hash_params);
+ spin_unlock(&pag->pag_buf_lock);
+ xfs_perag_put(pag);
+ freebuf = true;
+ }
+
+out_unlock:
+ spin_unlock(&bp->b_lock);
+
+ if (freebuf)
+ xfs_buf_free(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_target->bt_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(
+ xfs_buf_t *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);
+}
+
+/*
+ * Buffer Utility Routines
+ */
+
+void
+xfs_buf_ioend(
+ struct xfs_buf *bp)
+{
+ bool read = bp->b_flags & XBF_READ;
+
+ trace_xfs_buf_iodone(bp, _RET_IP_);
+
+ bp->b_flags &= ~(XBF_READ | XBF_WRITE | XBF_READ_AHEAD);
+
+ /*
+ * 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);
+
+ /* Only validate buffers that were read without errors */
+ if (read && !bp->b_error && bp->b_ops) {
+ ASSERT(!bp->b_iodone);
+ bp->b_ops->verify_read(bp);
+ }
+
+ if (!bp->b_error)
+ bp->b_flags |= XBF_DONE;
+
+ if (bp->b_iodone)
+ (*(bp->b_iodone))(bp);
+ else 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, xfs_buf_t, 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_ioend_wq, &bp->b_ioend_work);
+}
+
+void
+__xfs_buf_ioerror(
+ xfs_buf_t *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,
+ const char *func)
+{
+ xfs_alert(bp->b_target->bt_mount,
+"metadata I/O error in \"%s\" at daddr 0x%llx len %d error %d",
+ func, (uint64_t)XFS_BUF_ADDR(bp), bp->b_length,
+ -bp->b_error);
+}
+
+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_WRITE_FAIL | XBF_DONE);
+
+ error = xfs_buf_submit(bp);
+ if (error) {
+ xfs_force_shutdown(bp->b_target->bt_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;
+
+ /*
+ * 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,
+ int op,
+ int op_flags)
+{
+ int page_index;
+ 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 = min(total_nr_pages, BIO_MAX_PAGES);
+
+ bio = bio_alloc(GFP_NOIO, nr_pages);
+ bio_set_dev(bio, bp->b_target->bt_bdev);
+ bio->bi_iter.bi_sector = sector;
+ bio->bi_end_io = xfs_buf_bio_end_io;
+ bio->bi_private = bp;
+ bio_set_op_attrs(bio, op, op_flags);
+
+ 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;
+ int op;
+ int op_flags = 0;
+ 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;
+
+ /*
+ * Initialize the I/O completion workqueue if we haven't yet or the
+ * submitter has not opted to specify a custom one.
+ */
+ if (!bp->b_ioend_wq)
+ bp->b_ioend_wq = bp->b_target->bt_mount->m_buf_workqueue;
+
+ if (bp->b_flags & XBF_WRITE) {
+ op = REQ_OP_WRITE;
+ if (bp->b_flags & XBF_SYNCIO)
+ op_flags = REQ_SYNC;
+ if (bp->b_flags & XBF_FUA)
+ op_flags |= REQ_FUA;
+ if (bp->b_flags & XBF_FLUSH)
+ op_flags |= REQ_PREFLUSH;
+
+ /*
+ * 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_target->bt_mount,
+ SHUTDOWN_CORRUPT_INCORE);
+ return;
+ }
+ } else if (bp->b_bn != XFS_BUF_DADDR_NULL) {
+ struct xfs_mount *mp = bp->b_target->bt_mount;
+
+ /*
+ * non-crc filesystems don't attach verifiers during
+ * log recovery, so don't warn for such filesystems.
+ */
+ if (xfs_sb_version_hascrc(&mp->m_sb)) {
+ xfs_warn(mp,
+ "%s: no buf ops on daddr 0x%llx len %d",
+ __func__, bp->b_bn, bp->b_length);
+ xfs_hex_dump(bp->b_addr,
+ XFS_CORRUPTION_DUMP_LEN);
+ dump_stack();
+ }
+ }
+ } else if (bp->b_flags & XBF_READ_AHEAD) {
+ op = REQ_OP_READ;
+ op_flags = REQ_RAHEAD;
+ } else {
+ op = REQ_OP_READ;
+ }
+
+ /* we only use the buffer cache for meta-data */
+ op_flags |= REQ_META;
+
+ /*
+ * 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_io_length);
+ blk_start_plug(&plug);
+ for (i = 0; i < bp->b_map_count; i++) {
+ xfs_buf_ioapply_map(bp, i, &offset, &size, op, op_flags);
+ 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.
+ */
+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 shutdown we stale and complete the buffer immediately */
+ if (XFS_FORCED_SHUTDOWN(bp->b_target->bt_mount)) {
+ xfs_buf_ioerror(bp, -EIO);
+ bp->b_flags &= ~XBF_DONE;
+ xfs_buf_stale(bp);
+ if (bp->b_flags & XBF_ASYNC)
+ xfs_buf_ioend(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;
+
+ offset += bp->b_offset;
+ page = bp->b_pages[offset >> PAGE_SHIFT];
+ return page_address(page) + (offset & (PAGE_SIZE-1));
+}
+
+/*
+ * Move data into or out of a buffer.
+ */
+void
+xfs_buf_iomove(
+ xfs_buf_t *bp, /* buffer to process */
+ size_t boff, /* starting buffer offset */
+ size_t bsize, /* length to copy */
+ void *data, /* data address */
+ xfs_buf_rw_t mode) /* read/write/zero flag */
+{
+ 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_io_length) - boff);
+
+ ASSERT((csize + page_offset) <= PAGE_SIZE);
+
+ switch (mode) {
+ case XBRW_ZERO:
+ memset(page_address(page) + page_offset, 0, csize);
+ break;
+ case XBRW_READ:
+ memcpy(data, page_address(page) + page_offset, csize);
+ break;
+ case XBRW_WRITE:
+ memcpy(page_address(page) + page_offset, data, csize);
+ }
+
+ boff += csize;
+ data += csize;
+ }
+}
+
+/*
+ * 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_wait_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_wait_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;
+}
+
+void
+xfs_wait_buftarg(
+ struct xfs_buftarg *btp)
+{
+ LIST_HEAD(dispose);
+ int loop = 0;
+
+ /*
+ * 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);
+
+ /* 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_wait_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) {
+ xfs_alert(btp->bt_mount,
+"Corruption Alert: Buffer at daddr 0x%llx had permanent write failures!",
+ (long long)bp->b_bn);
+ xfs_alert(btp->bt_mount,
+"Please run xfs_repair to determine the extent of the problem.");
+ }
+ xfs_buf_rele(bp);
+ }
+ if (loop++ != 0)
+ delay(100);
+ }
+}
+
+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 = container_of(shrink,
+ struct xfs_buftarg, bt_shrinker);
+ 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 = container_of(shrink,
+ struct xfs_buftarg, bt_shrinker);
+ return list_lru_shrink_count(&btp->bt_lru, sc);
+}
+
+void
+xfs_free_buftarg(
+ struct xfs_buftarg *btp)
+{
+ unregister_shrinker(&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);
+
+ xfs_blkdev_issue_flush(btp);
+
+ kmem_free(btp);
+}
+
+int
+xfs_setsize_buftarg(
+ xfs_buftarg_t *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, sectorsize)) {
+ xfs_warn(btp->bt_mount,
+ "Cannot set_blocksize to %u on device %pg",
+ sectorsize, btp->bt_bdev);
+ return -EINVAL;
+ }
+
+ /* Set up device logical sector size mask */
+ btp->bt_logical_sectorsize = bdev_logical_block_size(btp->bt_bdev);
+ btp->bt_logical_sectormask = bdev_logical_block_size(btp->bt_bdev) - 1;
+
+ return 0;
+}
+
+/*
+ * When allocating the initial buffer target we have not yet
+ * read in the superblock, so don't know what sized sectors
+ * are being used at this early stage. Play safe.
+ */
+STATIC int
+xfs_setsize_buftarg_early(
+ xfs_buftarg_t *btp,
+ struct block_device *bdev)
+{
+ return xfs_setsize_buftarg(btp, bdev_logical_block_size(bdev));
+}
+
+xfs_buftarg_t *
+xfs_alloc_buftarg(
+ struct xfs_mount *mp,
+ struct block_device *bdev,
+ struct dax_device *dax_dev)
+{
+ xfs_buftarg_t *btp;
+
+ btp = kmem_zalloc(sizeof(*btp), KM_SLEEP | KM_NOFS);
+
+ btp->bt_mount = mp;
+ btp->bt_dev = bdev->bd_dev;
+ btp->bt_bdev = bdev;
+ btp->bt_daxdev = dax_dev;
+
+ if (xfs_setsize_buftarg_early(btp, bdev))
+ goto error_free;
+
+ if (list_lru_init(&btp->bt_lru))
+ goto error_free;
+
+ if (percpu_counter_init(&btp->bt_io_count, 0, GFP_KERNEL))
+ goto error_lru;
+
+ btp->bt_shrinker.count_objects = xfs_buftarg_shrink_count;
+ btp->bt_shrinker.scan_objects = xfs_buftarg_shrink_scan;
+ btp->bt_shrinker.seeks = DEFAULT_SEEKS;
+ btp->bt_shrinker.flags = SHRINKER_NUMA_AWARE;
+ if (register_shrinker(&btp->bt_shrinker))
+ goto error_pcpu;
+ return btp;
+
+error_pcpu:
+ percpu_counter_destroy(&btp->bt_io_count);
+error_lru:
+ list_lru_destroy(&btp->bt_lru);
+error_free:
+ kmem_free(btp);
+ return NULL;
+}
+
+/*
+ * 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;
+ list_del_init(&bp->b_list);
+ 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;
+}
+
+/*
+ * 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,
+ struct list_head *a,
+ 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;
+ LIST_HEAD (submit_list);
+ 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_ispinned(bp)) {
+ pinned++;
+ continue;
+ }
+ if (!xfs_buf_trylock(bp))
+ 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)) {
+ list_del_init(&bp->b_list);
+ 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 | XBF_WRITE_FAIL);
+ 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;
+ list_del_init(&bp->b_list);
+ }
+ __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.
+ */
+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);
+
+ list_del_init(&bp->b_list);
+
+ /*
+ * 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;
+}
+
+int __init
+xfs_buf_init(void)
+{
+ xfs_buf_zone = kmem_zone_init_flags(sizeof(xfs_buf_t), "xfs_buf",
+ KM_ZONE_HWALIGN, NULL);
+ if (!xfs_buf_zone)
+ goto out;
+
+ return 0;
+
+ out:
+ return -ENOMEM;
+}
+
+void
+xfs_buf_terminate(void)
+{
+ kmem_zone_destroy(xfs_buf_zone);
+}
+
+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_target->bt_mount,
+ XFS_ERRTAG_BUF_LRU_REF))
+ lru_ref = 0;
+
+ atomic_set(&bp->b_lru_ref, lru_ref);
+}