The patch titled
Subject: iomap: protect read_bytes_pending with the state_lock
has been added to the -mm mm-unstable branch. Its filename is
iomap-protect-read_bytes_pending-with-the-state_lock.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/iomap-protect-read_bytes_pending-with-the-state_lock.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: "Matthew Wilcox (Oracle)" <willy@xxxxxxxxxxxxx>
Subject: iomap: protect read_bytes_pending with the state_lock
Date: Wed, 4 Oct 2023 17:53:02 +0100
Perform one atomic operation (acquiring the spinlock) instead of two
(spinlock & atomic_sub) per read completion.
Link: https://lkml.kernel.org/r/20231004165317.1061855-3-willy@xxxxxxxxxxxxx
Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Cc: Albert Ou <aou@xxxxxxxxxxxxxxxxx>
Cc: Alexander Gordeev <agordeev@xxxxxxxxxxxxx>
Cc: Andreas Dilger <adilger.kernel@xxxxxxxxx>
Cc: Christian Borntraeger <borntraeger@xxxxxxxxxxxxx>
Cc: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
Cc: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
Cc: Heiko Carstens <hca@xxxxxxxxxxxxx>
Cc: Ivan Kokshaysky <ink@xxxxxxxxxxxxxxxxxxxx>
Cc: Matt Turner <mattst88@xxxxxxxxx>
Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Cc: Nicholas Piggin <npiggin@xxxxxxxxx>
Cc: Palmer Dabbelt <palmer@xxxxxxxxxxx>
Cc: Paul Walmsley <paul.walmsley@xxxxxxxxxx>
Cc: Richard Henderson <richard.henderson@xxxxxxxxxx>
Cc: Sven Schnelle <svens@xxxxxxxxxxxxx>
Cc: "Theodore Ts'o" <tytso@xxxxxxx>
Cc: Thomas Bogendoerfer <tsbogend@xxxxxxxxxxxxxxxx>
Cc: Vasily Gorbik <gor@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/iomap/buffered-io.c | 37 +++++++++++++++++++++++++------------
1 file changed, 25 insertions(+), 12 deletions(-)
--- a/fs/iomap/buffered-io.c~iomap-protect-read_bytes_pending-with-the-state_lock
+++ a/fs/iomap/buffered-io.c
@@ -29,9 +29,9 @@ typedef int (*iomap_punch_t)(struct inod
* and I/O completions.
*/
struct iomap_folio_state {
- atomic_t read_bytes_pending;
- atomic_t write_bytes_pending;
spinlock_t state_lock;
+ unsigned int read_bytes_pending;
+ atomic_t write_bytes_pending;
/*
* Each block has two bits in this bitmap:
@@ -183,7 +183,7 @@ static void ifs_free(struct folio *folio
if (!ifs)
return;
- WARN_ON_ONCE(atomic_read(&ifs->read_bytes_pending));
+ WARN_ON_ONCE(ifs->read_bytes_pending != 0);
WARN_ON_ONCE(atomic_read(&ifs->write_bytes_pending));
WARN_ON_ONCE(ifs_is_fully_uptodate(folio, ifs) !=
folio_test_uptodate(folio));
@@ -250,19 +250,29 @@ static void iomap_adjust_read_range(stru
*lenp = plen;
}
-static void iomap_finish_folio_read(struct folio *folio, size_t offset,
+static void iomap_finish_folio_read(struct folio *folio, size_t off,
size_t len, int error)
{
struct iomap_folio_state *ifs = folio->private;
+ bool uptodate = !error;
+ bool finished = true;
- if (unlikely(error)) {
- folio_clear_uptodate(folio);
- folio_set_error(folio);
- } else {
- iomap_set_range_uptodate(folio, offset, len);
+ if (ifs) {
+ unsigned long flags;
+
+ spin_lock_irqsave(&ifs->state_lock, flags);
+ if (!error)
+ uptodate = ifs_set_range_uptodate(folio, ifs, off, len);
+ ifs->read_bytes_pending -= len;
+ finished = !ifs->read_bytes_pending;
+ spin_unlock_irqrestore(&ifs->state_lock, flags);
}
- if (!ifs || atomic_sub_and_test(len, &ifs->read_bytes_pending))
+ if (error)
+ folio_set_error(folio);
+ if (uptodate)
+ folio_mark_uptodate(folio);
+ if (finished)
folio_unlock(folio);
}
@@ -360,8 +370,11 @@ static loff_t iomap_readpage_iter(const
}
ctx->cur_folio_in_bio = true;
- if (ifs)
- atomic_add(plen, &ifs->read_bytes_pending);
+ if (ifs) {
+ spin_lock_irq(&ifs->state_lock);
+ ifs->read_bytes_pending += plen;
+ spin_unlock_irq(&ifs->state_lock);
+ }
sector = iomap_sector(iomap, pos);
if (!ctx->bio ||
_
Patches currently in -mm which might be from willy@xxxxxxxxxxxxx are
mm-make-lock_folio_maybe_drop_mmap-vma-lock-aware.patch
mm-call-wp_page_copy-under-the-vma-lock.patch
mm-handle-shared-faults-under-the-vma-lock.patch
mm-handle-cow-faults-under-the-vma-lock.patch
mm-handle-read-faults-under-the-vma-lock.patch
mm-handle-write-faults-to-ro-pages-under-the-vma-lock.patch
iomap-hold-state_lock-over-call-to-ifs_set_range_uptodate.patch
iomap-protect-read_bytes_pending-with-the-state_lock.patch
mm-add-folio_end_read.patch
ext4-use-folio_end_read.patch
buffer-use-folio_end_read.patch
iomap-use-folio_end_read.patch
bitops-add-xor_unlock_is_negative_byte.patch
alpha-implement-xor_unlock_is_negative_byte.patch
m68k-implement-xor_unlock_is_negative_byte.patch
mips-implement-xor_unlock_is_negative_byte.patch
powerpc-implement-arch_xor_unlock_is_negative_byte-on-32-bit.patch
riscv-implement-xor_unlock_is_negative_byte.patch
s390-implement-arch_xor_unlock_is_negative_byte.patch
mm-delete-checks-for-xor_unlock_is_negative_byte.patch
mm-add-folio_xor_flags_has_waiters.patch
mm-make-__end_folio_writeback-return-void.patch
mm-use-folio_xor_flags_has_waiters-in-folio_end_writeback.patch
