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Message-ID: <20250108192131.46843-1-me@davidreaver.com>
Date: Wed, 8 Jan 2025 11:21:30 -0800
From: David Reaver <me@...idreaver.com>
To: Song Liu <song@...nel.org>,
Yu Kuai <yukuai3@...wei.com>
Cc: David Reaver <me@...idreaver.com>,
linux-raid@...r.kernel.org,
linux-kernel@...r.kernel.org,
Krister Johansen <kjlx@...pleofstupid.com>,
Ira Weiny <ira.weiny@...el.com>,
Thomas Gleixner <tglx@...utronix.de>
Subject: [PATCH] md: Replace deprecated kmap_atomic() with kmap_local_page()
kmap_atomic() is deprecated and should be replaced with kmap_local_page()
[1][2]. kmap_local_page() is faster in kernels with HIGHMEM enabled, can
take page faults, and allows preemption.
According to [2], this is safe as long as the code between kmap_atomic()
and kunmap_atomic() does not implicitly depend on disabling page faults or
preemption. It appears to me that none of the call sites in this patch
depend on disabling page faults or preemption; they are all mapping a page
to simply extract some information from it or print some debug info.
[1] https://lwn.net/Articles/836144/
[2] https://docs.kernel.org/mm/highmem.html#temporary-virtual-mappings
Signed-off-by: David Reaver <me@...idreaver.com>
---
drivers/md/md-bitmap.c | 42 ++++++++++++++++++++--------------------
drivers/md/raid5-cache.c | 16 +++++++--------
2 files changed, 29 insertions(+), 29 deletions(-)
diff --git a/drivers/md/md-bitmap.c b/drivers/md/md-bitmap.c
index 29da10e6f703..1f8772b3b66c 100644
--- a/drivers/md/md-bitmap.c
+++ b/drivers/md/md-bitmap.c
@@ -682,7 +682,7 @@ static void bitmap_update_sb(void *data)
return;
if (!bitmap->storage.sb_page) /* no superblock */
return;
- sb = kmap_atomic(bitmap->storage.sb_page);
+ sb = kmap_local_page(bitmap->storage.sb_page);
sb->events = cpu_to_le64(bitmap->mddev->events);
if (bitmap->mddev->events < bitmap->events_cleared)
/* rocking back to read-only */
@@ -702,7 +702,7 @@ static void bitmap_update_sb(void *data)
sb->nodes = cpu_to_le32(bitmap->mddev->bitmap_info.nodes);
sb->sectors_reserved = cpu_to_le32(bitmap->mddev->
bitmap_info.space);
- kunmap_atomic(sb);
+ kunmap_local(sb);
if (bitmap->storage.file)
write_file_page(bitmap, bitmap->storage.sb_page, 1);
@@ -717,7 +717,7 @@ static void bitmap_print_sb(struct bitmap *bitmap)
if (!bitmap || !bitmap->storage.sb_page)
return;
- sb = kmap_atomic(bitmap->storage.sb_page);
+ sb = kmap_local_page(bitmap->storage.sb_page);
pr_debug("%s: bitmap file superblock:\n", bmname(bitmap));
pr_debug(" magic: %08x\n", le32_to_cpu(sb->magic));
pr_debug(" version: %u\n", le32_to_cpu(sb->version));
@@ -736,7 +736,7 @@ static void bitmap_print_sb(struct bitmap *bitmap)
pr_debug(" sync size: %llu KB\n",
(unsigned long long)le64_to_cpu(sb->sync_size)/2);
pr_debug("max write behind: %u\n", le32_to_cpu(sb->write_behind));
- kunmap_atomic(sb);
+ kunmap_local(sb);
}
/*
@@ -760,7 +760,7 @@ static int md_bitmap_new_disk_sb(struct bitmap *bitmap)
return -ENOMEM;
bitmap->storage.sb_index = 0;
- sb = kmap_atomic(bitmap->storage.sb_page);
+ sb = kmap_local_page(bitmap->storage.sb_page);
sb->magic = cpu_to_le32(BITMAP_MAGIC);
sb->version = cpu_to_le32(BITMAP_MAJOR_HI);
@@ -768,7 +768,7 @@ static int md_bitmap_new_disk_sb(struct bitmap *bitmap)
chunksize = bitmap->mddev->bitmap_info.chunksize;
BUG_ON(!chunksize);
if (!is_power_of_2(chunksize)) {
- kunmap_atomic(sb);
+ kunmap_local(sb);
pr_warn("bitmap chunksize not a power of 2\n");
return -EINVAL;
}
@@ -803,7 +803,7 @@ static int md_bitmap_new_disk_sb(struct bitmap *bitmap)
sb->events_cleared = cpu_to_le64(bitmap->mddev->events);
bitmap->mddev->bitmap_info.nodes = 0;
- kunmap_atomic(sb);
+ kunmap_local(sb);
return 0;
}
@@ -865,7 +865,7 @@ static int md_bitmap_read_sb(struct bitmap *bitmap)
return err;
err = -EINVAL;
- sb = kmap_atomic(sb_page);
+ sb = kmap_local_page(sb_page);
chunksize = le32_to_cpu(sb->chunksize);
daemon_sleep = le32_to_cpu(sb->daemon_sleep) * HZ;
@@ -932,7 +932,7 @@ static int md_bitmap_read_sb(struct bitmap *bitmap)
err = 0;
out:
- kunmap_atomic(sb);
+ kunmap_local(sb);
if (err == 0 && nodes && (bitmap->cluster_slot < 0)) {
/* Assigning chunksize is required for "re_read" */
bitmap->mddev->bitmap_info.chunksize = chunksize;
@@ -1161,12 +1161,12 @@ static void md_bitmap_file_set_bit(struct bitmap *bitmap, sector_t block)
bit = file_page_offset(&bitmap->storage, chunk);
/* set the bit */
- kaddr = kmap_atomic(page);
+ kaddr = kmap_local_page(page);
if (test_bit(BITMAP_HOSTENDIAN, &bitmap->flags))
set_bit(bit, kaddr);
else
set_bit_le(bit, kaddr);
- kunmap_atomic(kaddr);
+ kunmap_local(kaddr);
pr_debug("set file bit %lu page %lu\n", bit, index);
/* record page number so it gets flushed to disk when unplug occurs */
set_page_attr(bitmap, index - node_offset, BITMAP_PAGE_DIRTY);
@@ -1190,12 +1190,12 @@ static void md_bitmap_file_clear_bit(struct bitmap *bitmap, sector_t block)
if (!page)
return;
bit = file_page_offset(&bitmap->storage, chunk);
- paddr = kmap_atomic(page);
+ paddr = kmap_local_page(page);
if (test_bit(BITMAP_HOSTENDIAN, &bitmap->flags))
clear_bit(bit, paddr);
else
clear_bit_le(bit, paddr);
- kunmap_atomic(paddr);
+ kunmap_local(paddr);
if (!test_page_attr(bitmap, index - node_offset, BITMAP_PAGE_NEEDWRITE)) {
set_page_attr(bitmap, index - node_offset, BITMAP_PAGE_PENDING);
bitmap->allclean = 0;
@@ -1214,12 +1214,12 @@ static int md_bitmap_file_test_bit(struct bitmap *bitmap, sector_t block)
if (!page)
return -EINVAL;
bit = file_page_offset(&bitmap->storage, chunk);
- paddr = kmap_atomic(page);
+ paddr = kmap_local_page(page);
if (test_bit(BITMAP_HOSTENDIAN, &bitmap->flags))
set = test_bit(bit, paddr);
else
set = test_bit_le(bit, paddr);
- kunmap_atomic(paddr);
+ kunmap_local(paddr);
return set;
}
@@ -1387,9 +1387,9 @@ static int md_bitmap_init_from_disk(struct bitmap *bitmap, sector_t start)
* If the bitmap is out of date, dirty the whole page
* and write it out
*/
- paddr = kmap_atomic(page);
+ paddr = kmap_local_page(page);
memset(paddr + offset, 0xff, PAGE_SIZE - offset);
- kunmap_atomic(paddr);
+ kunmap_local(paddr);
filemap_write_page(bitmap, i, true);
if (test_bit(BITMAP_WRITE_ERROR, &bitmap->flags)) {
@@ -1405,12 +1405,12 @@ static int md_bitmap_init_from_disk(struct bitmap *bitmap, sector_t start)
void *paddr;
bool was_set;
- paddr = kmap_atomic(page);
+ paddr = kmap_local_page(page);
if (test_bit(BITMAP_HOSTENDIAN, &bitmap->flags))
was_set = test_bit(bit, paddr);
else
was_set = test_bit_le(bit, paddr);
- kunmap_atomic(paddr);
+ kunmap_local(paddr);
if (was_set) {
/* if the disk bit is set, set the memory bit */
@@ -1545,10 +1545,10 @@ static void bitmap_daemon_work(struct mddev *mddev)
bitmap_super_t *sb;
bitmap->need_sync = 0;
if (bitmap->storage.filemap) {
- sb = kmap_atomic(bitmap->storage.sb_page);
+ sb = kmap_local_page(bitmap->storage.sb_page);
sb->events_cleared =
cpu_to_le64(bitmap->events_cleared);
- kunmap_atomic(sb);
+ kunmap_local(sb);
set_page_attr(bitmap, 0,
BITMAP_PAGE_NEEDWRITE);
}
diff --git a/drivers/md/raid5-cache.c b/drivers/md/raid5-cache.c
index b4f7b79fd187..7a22cb2e5ac3 100644
--- a/drivers/md/raid5-cache.c
+++ b/drivers/md/raid5-cache.c
@@ -1023,10 +1023,10 @@ int r5l_write_stripe(struct r5l_log *log, struct stripe_head *sh)
/* checksum is already calculated in last run */
if (test_bit(STRIPE_LOG_TRAPPED, &sh->state))
continue;
- addr = kmap_atomic(sh->dev[i].page);
+ addr = kmap_local_page(sh->dev[i].page);
sh->dev[i].log_checksum = crc32c_le(log->uuid_checksum,
addr, PAGE_SIZE);
- kunmap_atomic(addr);
+ kunmap_local(addr);
}
parity_pages = 1 + !!(sh->qd_idx >= 0);
data_pages = write_disks - parity_pages;
@@ -1979,9 +1979,9 @@ r5l_recovery_verify_data_checksum(struct r5l_log *log,
u32 checksum;
r5l_recovery_read_page(log, ctx, page, log_offset);
- addr = kmap_atomic(page);
+ addr = kmap_local_page(page);
checksum = crc32c_le(log->uuid_checksum, addr, PAGE_SIZE);
- kunmap_atomic(addr);
+ kunmap_local(addr);
return (le32_to_cpu(log_checksum) == checksum) ? 0 : -EINVAL;
}
@@ -2381,11 +2381,11 @@ r5c_recovery_rewrite_data_only_stripes(struct r5l_log *log,
payload->size = cpu_to_le32(BLOCK_SECTORS);
payload->location = cpu_to_le64(
raid5_compute_blocknr(sh, i, 0));
- addr = kmap_atomic(dev->page);
+ addr = kmap_local_page(dev->page);
payload->checksum[0] = cpu_to_le32(
crc32c_le(log->uuid_checksum, addr,
PAGE_SIZE));
- kunmap_atomic(addr);
+ kunmap_local(addr);
sync_page_io(log->rdev, write_pos, PAGE_SIZE,
dev->page, REQ_OP_WRITE, false);
write_pos = r5l_ring_add(log, write_pos,
@@ -2888,10 +2888,10 @@ int r5c_cache_data(struct r5l_log *log, struct stripe_head *sh)
if (!test_bit(R5_Wantwrite, &sh->dev[i].flags))
continue;
- addr = kmap_atomic(sh->dev[i].page);
+ addr = kmap_local_page(sh->dev[i].page);
sh->dev[i].log_checksum = crc32c_le(log->uuid_checksum,
addr, PAGE_SIZE);
- kunmap_atomic(addr);
+ kunmap_local(addr);
pages++;
}
WARN_ON(pages == 0);
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