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-rw-r--r--fs/dax.c74
1 files changed, 39 insertions, 35 deletions
diff --git a/fs/dax.c b/fs/dax.c
index f74386293632..e99e5f373c88 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -1,17 +1,9 @@
+// SPDX-License-Identifier: GPL-2.0-only
/*
* fs/dax.c - Direct Access filesystem code
* Copyright (c) 2013-2014 Intel Corporation
* Author: Matthew Wilcox <matthew.r.wilcox@intel.com>
* Author: Ross Zwisler <ross.zwisler@linux.intel.com>
- *
- * This program is free software; you can redistribute it and/or modify it
- * under the terms and conditions of the GNU General Public License,
- * version 2, as published by the Free Software Foundation.
- *
- * This program is distributed in the hope it will be useful, but WITHOUT
- * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
- * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
- * more details.
*/
#include <linux/atomic.h>
@@ -132,6 +124,15 @@ static int dax_is_empty_entry(void *entry)
}
/*
+ * true if the entry that was found is of a smaller order than the entry
+ * we were looking for
+ */
+static bool dax_is_conflict(void *entry)
+{
+ return entry == XA_RETRY_ENTRY;
+}
+
+/*
* DAX page cache entry locking
*/
struct exceptional_entry_key {
@@ -203,11 +204,13 @@ static void dax_wake_entry(struct xa_state *xas, void *entry, bool wake_all)
* Look up entry in page cache, wait for it to become unlocked if it
* is a DAX entry and return it. The caller must subsequently call
* put_unlocked_entry() if it did not lock the entry or dax_unlock_entry()
- * if it did.
+ * if it did. The entry returned may have a larger order than @order.
+ * If @order is larger than the order of the entry found in i_pages, this
+ * function returns a dax_is_conflict entry.
*
* Must be called with the i_pages lock held.
*/
-static void *get_unlocked_entry(struct xa_state *xas)
+static void *get_unlocked_entry(struct xa_state *xas, unsigned int order)
{
void *entry;
struct wait_exceptional_entry_queue ewait;
@@ -218,6 +221,8 @@ static void *get_unlocked_entry(struct xa_state *xas)
for (;;) {
entry = xas_find_conflict(xas);
+ if (dax_entry_order(entry) < order)
+ return XA_RETRY_ENTRY;
if (!entry || WARN_ON_ONCE(!xa_is_value(entry)) ||
!dax_is_locked(entry))
return entry;
@@ -262,7 +267,7 @@ static void wait_entry_unlocked(struct xa_state *xas, void *entry)
static void put_unlocked_entry(struct xa_state *xas, void *entry)
{
/* If we were the only waiter woken, wake the next one */
- if (entry)
+ if (entry && dax_is_conflict(entry))
dax_wake_entry(xas, entry, false);
}
@@ -469,7 +474,7 @@ void dax_unlock_page(struct page *page, dax_entry_t cookie)
* overlap with xarray value entries.
*/
static void *grab_mapping_entry(struct xa_state *xas,
- struct address_space *mapping, unsigned long size_flag)
+ struct address_space *mapping, unsigned int order)
{
unsigned long index = xas->xa_index;
bool pmd_downgrade = false; /* splitting PMD entry into PTE entries? */
@@ -477,20 +482,17 @@ static void *grab_mapping_entry(struct xa_state *xas,
retry:
xas_lock_irq(xas);
- entry = get_unlocked_entry(xas);
+ entry = get_unlocked_entry(xas, order);
if (entry) {
+ if (dax_is_conflict(entry))
+ goto fallback;
if (!xa_is_value(entry)) {
xas_set_err(xas, EIO);
goto out_unlock;
}
- if (size_flag & DAX_PMD) {
- if (dax_is_pte_entry(entry)) {
- put_unlocked_entry(xas, entry);
- goto fallback;
- }
- } else { /* trying to grab a PTE entry */
+ if (order == 0) {
if (dax_is_pmd_entry(entry) &&
(dax_is_zero_entry(entry) ||
dax_is_empty_entry(entry))) {
@@ -531,7 +533,11 @@ retry:
if (entry) {
dax_lock_entry(xas, entry);
} else {
- entry = dax_make_entry(pfn_to_pfn_t(0), size_flag | DAX_EMPTY);
+ unsigned long flags = DAX_EMPTY;
+
+ if (order > 0)
+ flags |= DAX_PMD;
+ entry = dax_make_entry(pfn_to_pfn_t(0), flags);
dax_lock_entry(xas, entry);
if (xas_error(xas))
goto out_unlock;
@@ -602,7 +608,7 @@ struct page *dax_layout_busy_page(struct address_space *mapping)
if (WARN_ON_ONCE(!xa_is_value(entry)))
continue;
if (unlikely(dax_is_locked(entry)))
- entry = get_unlocked_entry(&xas);
+ entry = get_unlocked_entry(&xas, 0);
if (entry)
page = dax_busy_page(entry);
put_unlocked_entry(&xas, entry);
@@ -629,7 +635,7 @@ static int __dax_invalidate_entry(struct address_space *mapping,
void *entry;
xas_lock_irq(&xas);
- entry = get_unlocked_entry(&xas);
+ entry = get_unlocked_entry(&xas, 0);
if (!entry || WARN_ON_ONCE(!xa_is_value(entry)))
goto out;
if (!trunc &&
@@ -728,12 +734,11 @@ static void *dax_insert_entry(struct xa_state *xas,
xas_reset(xas);
xas_lock_irq(xas);
- if (dax_entry_size(entry) != dax_entry_size(new_entry)) {
+ if (dax_is_zero_entry(entry) || dax_is_empty_entry(entry)) {
+ void *old;
+
dax_disassociate_entry(entry, mapping, false);
dax_associate_entry(new_entry, mapping, vmf->vma, vmf->address);
- }
-
- if (dax_is_zero_entry(entry) || dax_is_empty_entry(entry)) {
/*
* Only swap our new entry into the page cache if the current
* entry is a zero page or an empty entry. If a normal PTE or
@@ -742,7 +747,7 @@ static void *dax_insert_entry(struct xa_state *xas,
* existing entry is a PMD, we will just leave the PMD in the
* tree and dirty it if necessary.
*/
- void *old = dax_lock_entry(xas, new_entry);
+ old = dax_lock_entry(xas, new_entry);
WARN_ON_ONCE(old != xa_mk_value(xa_to_value(entry) |
DAX_LOCKED));
entry = new_entry;
@@ -857,7 +862,7 @@ static int dax_writeback_one(struct xa_state *xas, struct dax_device *dax_dev,
if (unlikely(dax_is_locked(entry))) {
void *old_entry = entry;
- entry = get_unlocked_entry(xas);
+ entry = get_unlocked_entry(xas, 0);
/* Entry got punched out / reallocated? */
if (!entry || WARN_ON_ONCE(!xa_is_value(entry)))
@@ -1196,7 +1201,7 @@ dax_iomap_rw(struct kiocb *iocb, struct iov_iter *iter,
unsigned flags = 0;
if (iov_iter_rw(iter) == WRITE) {
- lockdep_assert_held_exclusive(&inode->i_rwsem);
+ lockdep_assert_held_write(&inode->i_rwsem);
flags |= IOMAP_WRITE;
} else {
lockdep_assert_held(&inode->i_rwsem);
@@ -1518,7 +1523,7 @@ static vm_fault_t dax_iomap_pmd_fault(struct vm_fault *vmf, pfn_t *pfnp,
* entry is already in the array, for instance), it will return
* VM_FAULT_FALLBACK.
*/
- entry = grab_mapping_entry(&xas, mapping, DAX_PMD);
+ entry = grab_mapping_entry(&xas, mapping, PMD_ORDER);
if (xa_is_internal(entry)) {
result = xa_to_internal(entry);
goto fallback;
@@ -1667,11 +1672,10 @@ dax_insert_pfn_mkwrite(struct vm_fault *vmf, pfn_t pfn, unsigned int order)
vm_fault_t ret;
xas_lock_irq(&xas);
- entry = get_unlocked_entry(&xas);
+ entry = get_unlocked_entry(&xas, order);
/* Did we race with someone splitting entry or so? */
- if (!entry ||
- (order == 0 && !dax_is_pte_entry(entry)) ||
- (order == PMD_ORDER && !dax_is_pmd_entry(entry))) {
+ if (!entry || dax_is_conflict(entry) ||
+ (order == 0 && !dax_is_pte_entry(entry))) {
put_unlocked_entry(&xas, entry);
xas_unlock_irq(&xas);
trace_dax_insert_pfn_mkwrite_no_entry(mapping->host, vmf,
generated by cgit v1.2.3 (git 2.39.0) at 2024-12-16 00:39:26 +0300