Implement readahead callback for squashfs. It will read datablocks
which cover pages in readahead request. For a few cases it will
not mark page as uptodate, including:
- file end is 0.
- zero filled blocks.
- current batch of pages isn't in the same datablock or not enough in a
datablock.
Otherwise pages will be marked as uptodate. The unhandled pages will be
updated by readpage later.
Signed-off-by: Hsin-Yi Wang <[email protected]>
---
Note that this patch was not formally sent to the list before. It's
attached to email thread for discussion as it's still under development.
- v1:
The patch outline was suggested by Matthew. It went through a few
reviews by Matthew offline.
- v2:
https://lore.kernel.org/linux-mm/[email protected]/t/#m442435c149d411c5c9d8019cff5915419b04bf10
This is a resend of v1.
- v3:
https://lore.kernel.org/linux-mm/[email protected]/t/#m55a709e6ba5ec59fe95323a67a7f3d6b1953e470
Fix page actor size to avoid a crash from squashfs_decompress().
Suggested by Phillip Lougher[1]
[1] https://lore.kernel.org/linux-mm/[email protected]/t/#m687f82debb7667ff31982a05aef3eba081eb5039
- v4:
https://lore.kernel.org/linux-mm/[email protected]/t/#mf93267690ec2e841dade6a494fe72c84b61328d9
Fix to free page after used. Suggested by Xiongwei Song[2]
Refactor the skip page logic to possible improve the performance.
Suggested by Phillip Lougher[3]
[2] https://lore.kernel.org/linux-mm/[email protected]/t/#m0e7b33d167b1ef0eb39b9f41c32ed3f80dfced18
[3] https://lore.kernel.org/linux-mm/[email protected]/t/#m1e0a8f8e4a98d79d14c81b66e197b6dc0a3b77a1
---
fs/squashfs/file.c | 77 ++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 77 insertions(+)
diff --git a/fs/squashfs/file.c b/fs/squashfs/file.c
index a8e495d8eb86..91dfec792f4c 100644
--- a/fs/squashfs/file.c
+++ b/fs/squashfs/file.c
@@ -39,6 +39,7 @@
#include "squashfs_fs_sb.h"
#include "squashfs_fs_i.h"
#include "squashfs.h"
+#include "page_actor.h"
/*
* Locate cache slot in range [offset, index] for specified inode. If
@@ -495,7 +496,83 @@ static int squashfs_read_folio(struct file *file, struct folio *folio)
return 0;
}
+static void squashfs_readahead(struct readahead_control *ractl)
+{
+ struct inode *inode = ractl->mapping->host;
+ struct squashfs_sb_info *msblk = inode->i_sb->s_fs_info;
+ size_t mask = (1UL << msblk->block_log) - 1;
+ size_t shift = msblk->block_log - PAGE_SHIFT;
+ loff_t req_end = readahead_pos(ractl) + readahead_length(ractl);
+ loff_t start = readahead_pos(ractl) &~ mask;
+ size_t len = readahead_length(ractl) + readahead_pos(ractl) - start;
+ struct squashfs_page_actor *actor;
+ unsigned int nr_pages = 0;
+ struct page **pages;
+ u64 block = 0;
+ int bsize, res, i, index;
+ int file_end = i_size_read(inode) >> msblk->block_log;
+ unsigned int max_pages = 1UL << shift;
+
+ readahead_expand(ractl, start, (len | mask) + 1);
+
+ if (readahead_pos(ractl) + readahead_length(ractl) < req_end ||
+ file_end == 0)
+ return;
+
+ pages = kmalloc_array(max_pages, sizeof(void *), GFP_KERNEL);
+ if (!pages)
+ return;
+
+ actor = squashfs_page_actor_init_special(pages, max_pages, 0);
+ if (!actor)
+ goto out;
+
+ for (;;) {
+ nr_pages = __readahead_batch(ractl, pages, max_pages);
+ if (!nr_pages)
+ break;
+
+ if (readahead_pos(ractl) >= i_size_read(inode) ||
+ nr_pages < max_pages)
+ goto skip_pages;
+
+ index = pages[0]->index >> shift;
+ if ((pages[nr_pages - 1]->index >> shift) != index)
+ goto skip_pages;
+
+ bsize = read_blocklist(inode, index, &block);
+ if (bsize == 0)
+ goto skip_pages;
+
+ res = squashfs_read_data(inode->i_sb, block, bsize, NULL,
+ actor);
+
+ if (res >= 0)
+ for (i = 0; i < nr_pages; i++)
+ SetPageUptodate(pages[i]);
+
+ for (i = 0; i < nr_pages; i++) {
+ unlock_page(pages[i]);
+ put_page(pages[i]);
+ }
+ }
+
+ kfree(actor);
+ kfree(pages);
+ return;
+
+skip_pages:
+ for (i = 0; i < nr_pages; i++) {
+ unlock_page(pages[i]);
+ put_page(pages[i]);
+ }
+
+ kfree(actor);
+out:
+ kfree(pages);
+}
const struct address_space_operations squashfs_aops = {
.read_folio = squashfs_read_folio
+ .readahead = squashfs_readahead
};
--
2.36.0.550.gb090851708-goog
On Mon, May 16, 2022 at 8:36 PM Matthew Wilcox <[email protected]> wrote:
>
> On Mon, May 16, 2022 at 07:04:08PM +0800, Hsin-Yi Wang wrote:
> > > + loff_t req_end = readahead_pos(ractl) + readahead_length(ractl);
> > > + loff_t start = readahead_pos(ractl) &~ mask;
> > > + size_t len = readahead_length(ractl) + readahead_pos(ractl) - start;
> > > + struct squashfs_page_actor *actor;
> > > + unsigned int nr_pages = 0;
> > > + struct page **pages;
> > > + u64 block = 0;
> > > + int bsize, res, i, index;
> > > + int file_end = i_size_read(inode) >> msblk->block_log;
> > > + unsigned int max_pages = 1UL << shift;
> > > +
> > > + readahead_expand(ractl, start, (len | mask) + 1);
> > > +
> > > + if (readahead_pos(ractl) + readahead_length(ractl) < req_end ||
> > > + file_end == 0)
> > > + return;
>
> What's the first half of this condition supposed to be checking for?
> It seems to be checking whether readahead_expand() shrunk the range
> covered by the ractl, but readahead_expand() never does that, so I'm
> confused why you're checking for it.
hi Matthew,
This is to check if readahead_expand() expands as much as it's requested.
I didn't encounter the mismatch so far in my testing. If this check is
not necessary, it can be removed.
Hi Hsin-Yi,
Thank you for the patch! Perhaps something to improve:
[auto build test WARNING on next-20220513]
[cannot apply to akpm-mm/mm-everything v5.18-rc7 v5.18-rc6 v5.18-rc5 v5.18-rc7]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]
url: https://github.com/intel-lab-lkp/linux/commits/Hsin-Yi-Wang/Implement-readahead-for-squashfs/20220516-185438
base: 1e1b28b936aed946122b4e0991e7144fdbbfd77e
config: m68k-allyesconfig (https://download.01.org/0day-ci/archive/20220516/[email protected]/config)
compiler: m68k-linux-gcc (GCC) 11.3.0
reproduce (this is a W=1 build):
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# https://github.com/intel-lab-lkp/linux/commit/573e1f2ced0df097c30c595d5bf5a9e7a5fcb8d5
git remote add linux-review https://github.com/intel-lab-lkp/linux
git fetch --no-tags linux-review Hsin-Yi-Wang/Implement-readahead-for-squashfs/20220516-185438
git checkout 573e1f2ced0df097c30c595d5bf5a9e7a5fcb8d5
# save the config file
mkdir build_dir && cp config build_dir/.config
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-11.3.0 make.cross W=1 O=build_dir ARCH=m68k SHELL=/bin/bash fs/squashfs/
If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <[email protected]>
All warnings (new ones prefixed by >>):
fs/squashfs/file.c: In function 'squashfs_readahead':
fs/squashfs/file.c:526:17: error: implicit declaration of function 'squashfs_page_actor_init_special'; did you mean 'squashfs_page_actor_init'? [-Werror=implicit-function-declaration]
526 | actor = squashfs_page_actor_init_special(pages, max_pages, 0);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
| squashfs_page_actor_init
>> fs/squashfs/file.c:526:15: warning: assignment to 'struct squashfs_page_actor *' from 'int' makes pointer from integer without a cast [-Wint-conversion]
526 | actor = squashfs_page_actor_init_special(pages, max_pages, 0);
| ^
fs/squashfs/file.c: At top level:
fs/squashfs/file.c:577:9: error: request for member 'readahead' in something not a structure or union
577 | .readahead = squashfs_readahead
| ^
cc1: some warnings being treated as errors
vim +526 fs/squashfs/file.c
498
499 static void squashfs_readahead(struct readahead_control *ractl)
500 {
501 struct inode *inode = ractl->mapping->host;
502 struct squashfs_sb_info *msblk = inode->i_sb->s_fs_info;
503 size_t mask = (1UL << msblk->block_log) - 1;
504 size_t shift = msblk->block_log - PAGE_SHIFT;
505 loff_t req_end = readahead_pos(ractl) + readahead_length(ractl);
506 loff_t start = readahead_pos(ractl) &~ mask;
507 size_t len = readahead_length(ractl) + readahead_pos(ractl) - start;
508 struct squashfs_page_actor *actor;
509 unsigned int nr_pages = 0;
510 struct page **pages;
511 u64 block = 0;
512 int bsize, res, i, index;
513 int file_end = i_size_read(inode) >> msblk->block_log;
514 unsigned int max_pages = 1UL << shift;
515
516 readahead_expand(ractl, start, (len | mask) + 1);
517
518 if (readahead_pos(ractl) + readahead_length(ractl) < req_end ||
519 file_end == 0)
520 return;
521
522 pages = kmalloc_array(max_pages, sizeof(void *), GFP_KERNEL);
523 if (!pages)
524 return;
525
> 526 actor = squashfs_page_actor_init_special(pages, max_pages, 0);
527 if (!actor)
528 goto out;
529
530 for (;;) {
531 nr_pages = __readahead_batch(ractl, pages, max_pages);
532 if (!nr_pages)
533 break;
534
535 if (readahead_pos(ractl) >= i_size_read(inode) ||
536 nr_pages < max_pages)
537 goto skip_pages;
538
539 index = pages[0]->index >> shift;
540 if ((pages[nr_pages - 1]->index >> shift) != index)
541 goto skip_pages;
542
543 bsize = read_blocklist(inode, index, &block);
544 if (bsize == 0)
545 goto skip_pages;
546
547 res = squashfs_read_data(inode->i_sb, block, bsize, NULL,
548 actor);
549
550 if (res >= 0)
551 for (i = 0; i < nr_pages; i++)
552 SetPageUptodate(pages[i]);
553
554 for (i = 0; i < nr_pages; i++) {
555 unlock_page(pages[i]);
556 put_page(pages[i]);
557 }
558 }
559
560 kfree(actor);
561 kfree(pages);
562 return;
563
564 skip_pages:
565 for (i = 0; i < nr_pages; i++) {
566 unlock_page(pages[i]);
567 put_page(pages[i]);
568 }
569
570 kfree(actor);
571 out:
572 kfree(pages);
573 }
574
--
0-DAY CI Kernel Test Service
https://01.org/lkp
On 16/05/2022 15:21, kernel test robot wrote:
> Hi Hsin-Yi,
>
> Thank you for the patch! Perhaps something to improve:
>
> [auto build test WARNING on next-20220513]
> [cannot apply to akpm-mm/mm-everything v5.18-rc7 v5.18-rc6 v5.18-rc5 v5.18-rc7]
> [If your patch is applied to the wrong git tree, kindly drop us a note.
> And when submitting patch, we suggest to use '--base' as documented in
> https://git-scm.com/docs/git-format-patch]
>
This is fixed by
[PATCH 3/2] squashfs: always build "file direct" version of page actor
Which I have just sent.
Phillip
> url: https://github.com/intel-lab-lkp/linux/commits/Hsin-Yi-Wang/Implement-readahead-for-squashfs/20220516-185438
> base: 1e1b28b936aed946122b4e0991e7144fdbbfd77e
> config: m68k-allyesconfig (https://download.01.org/0day-ci/archive/20220516/[email protected]/config)
> compiler: m68k-linux-gcc (GCC) 11.3.0
> reproduce (this is a W=1 build):
> wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
> chmod +x ~/bin/make.cross
> # https://github.com/intel-lab-lkp/linux/commit/573e1f2ced0df097c30c595d5bf5a9e7a5fcb8d5
> git remote add linux-review https://github.com/intel-lab-lkp/linux
> git fetch --no-tags linux-review Hsin-Yi-Wang/Implement-readahead-for-squashfs/20220516-185438
> git checkout 573e1f2ced0df097c30c595d5bf5a9e7a5fcb8d5
> # save the config file
> mkdir build_dir && cp config build_dir/.config
> COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-11.3.0 make.cross W=1 O=build_dir ARCH=m68k SHELL=/bin/bash fs/squashfs/
>
> If you fix the issue, kindly add following tag as appropriate
> Reported-by: kernel test robot <[email protected]>
>
> All warnings (new ones prefixed by >>):
>
> fs/squashfs/file.c: In function 'squashfs_readahead':
> fs/squashfs/file.c:526:17: error: implicit declaration of function 'squashfs_page_actor_init_special'; did you mean 'squashfs_page_actor_init'? [-Werror=implicit-function-declaration]
> 526 | actor = squashfs_page_actor_init_special(pages, max_pages, 0);
> | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> | squashfs_page_actor_init
>>> fs/squashfs/file.c:526:15: warning: assignment to 'struct squashfs_page_actor *' from 'int' makes pointer from integer without a cast [-Wint-conversion]
> 526 | actor = squashfs_page_actor_init_special(pages, max_pages, 0);
> | ^
> fs/squashfs/file.c: At top level:
> fs/squashfs/file.c:577:9: error: request for member 'readahead' in something not a structure or union
> 577 | .readahead = squashfs_readahead
> | ^
> cc1: some warnings being treated as errors
>
>
> vim +526 fs/squashfs/file.c
>
> 498
> 499 static void squashfs_readahead(struct readahead_control *ractl)
> 500 {
> 501 struct inode *inode = ractl->mapping->host;
> 502 struct squashfs_sb_info *msblk = inode->i_sb->s_fs_info;
> 503 size_t mask = (1UL << msblk->block_log) - 1;
> 504 size_t shift = msblk->block_log - PAGE_SHIFT;
> 505 loff_t req_end = readahead_pos(ractl) + readahead_length(ractl);
> 506 loff_t start = readahead_pos(ractl) &~ mask;
> 507 size_t len = readahead_length(ractl) + readahead_pos(ractl) - start;
> 508 struct squashfs_page_actor *actor;
> 509 unsigned int nr_pages = 0;
> 510 struct page **pages;
> 511 u64 block = 0;
> 512 int bsize, res, i, index;
> 513 int file_end = i_size_read(inode) >> msblk->block_log;
> 514 unsigned int max_pages = 1UL << shift;
> 515
> 516 readahead_expand(ractl, start, (len | mask) + 1);
> 517
> 518 if (readahead_pos(ractl) + readahead_length(ractl) < req_end ||
> 519 file_end == 0)
> 520 return;
> 521
> 522 pages = kmalloc_array(max_pages, sizeof(void *), GFP_KERNEL);
> 523 if (!pages)
> 524 return;
> 525
> > 526 actor = squashfs_page_actor_init_special(pages, max_pages, 0);
> 527 if (!actor)
> 528 goto out;
> 529
> 530 for (;;) {
> 531 nr_pages = __readahead_batch(ractl, pages, max_pages);
> 532 if (!nr_pages)
> 533 break;
> 534
> 535 if (readahead_pos(ractl) >= i_size_read(inode) ||
> 536 nr_pages < max_pages)
> 537 goto skip_pages;
> 538
> 539 index = pages[0]->index >> shift;
> 540 if ((pages[nr_pages - 1]->index >> shift) != index)
> 541 goto skip_pages;
> 542
> 543 bsize = read_blocklist(inode, index, &block);
> 544 if (bsize == 0)
> 545 goto skip_pages;
> 546
> 547 res = squashfs_read_data(inode->i_sb, block, bsize, NULL,
> 548 actor);
> 549
> 550 if (res >= 0)
> 551 for (i = 0; i < nr_pages; i++)
> 552 SetPageUptodate(pages[i]);
> 553
> 554 for (i = 0; i < nr_pages; i++) {
> 555 unlock_page(pages[i]);
> 556 put_page(pages[i]);
> 557 }
> 558 }
> 559
> 560 kfree(actor);
> 561 kfree(pages);
> 562 return;
> 563
> 564 skip_pages:
> 565 for (i = 0; i < nr_pages; i++) {
> 566 unlock_page(pages[i]);
> 567 put_page(pages[i]);
> 568 }
> 569
> 570 kfree(actor);
> 571 out:
> 572 kfree(pages);
> 573 }
> 574
>