| Message ID | 20201210063905.75727-16-wqu@suse.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | btrfs: add read-only support for subpage sector size | expand |
Hi Qu,
Thank you for the patch! Yet something to improve:
[auto build test ERROR on kdave/for-next]
[also build test ERROR on next-20201209]
[cannot apply to btrfs/next v5.10-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/0day-ci/linux/commits/Qu-Wenruo/btrfs-add-read-only-support-for-subpage-sector-size/20201210-144442
base: https://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux.git for-next
config: nds32-randconfig-r004-20201209 (attached as .config)
compiler: nds32le-linux-gcc (GCC) 9.3.0
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/0day-ci/linux/commit/e01cdf51d0d32647697616c0dd08f2cc3220bde4
git remote add linux-review https://github.com/0day-ci/linux
git fetch --no-tags linux-review Qu-Wenruo/btrfs-add-read-only-support-for-subpage-sector-size/20201210-144442
git checkout e01cdf51d0d32647697616c0dd08f2cc3220bde4
# save the attached .config to linux build tree
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=nds32
If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>
All errors (new ones prefixed by >>):
nds32le-linux-ld: fs/btrfs/disk-io.o: in function `btrfs_validate_metadata_buffer':
disk-io.c:(.text+0x4200): undefined reference to `__udivdi3'
>> nds32le-linux-ld: disk-io.c:(.text+0x4204): undefined reference to `__udivdi3'
---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org
Hi Qu,
Thank you for the patch! Yet something to improve:
[auto build test ERROR on kdave/for-next]
[also build test ERROR on next-20201210]
[cannot apply to v5.10-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/0day-ci/linux/commits/Qu-Wenruo/btrfs-add-read-only-support-for-subpage-sector-size/20201210-144442
base: https://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux.git for-next
config: i386-randconfig-a013-20201209 (attached as .config)
compiler: gcc-9 (Debian 9.3.0-15) 9.3.0
reproduce (this is a W=1 build):
# https://github.com/0day-ci/linux/commit/e01cdf51d0d32647697616c0dd08f2cc3220bde4
git remote add linux-review https://github.com/0day-ci/linux
git fetch --no-tags linux-review Qu-Wenruo/btrfs-add-read-only-support-for-subpage-sector-size/20201210-144442
git checkout e01cdf51d0d32647697616c0dd08f2cc3220bde4
# save the attached .config to linux build tree
make W=1 ARCH=i386
If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>
All errors (new ones prefixed by >>):
ld: fs/btrfs/disk-io.o: in function `validate_subpage_buffer':
>> fs/btrfs/disk-io.c:619: undefined reference to `__udivdi3'
vim +619 fs/btrfs/disk-io.c
593
594 static int validate_subpage_buffer(struct page *page, u64 start, u64 end,
595 int mirror)
596 {
597 struct btrfs_fs_info *fs_info = btrfs_sb(page->mapping->host->i_sb);
598 struct extent_buffer *eb;
599 int reads_done;
600 int ret = 0;
601
602 if (!IS_ALIGNED(start, fs_info->sectorsize) ||
603 !IS_ALIGNED(end - start + 1, fs_info->sectorsize) ||
604 !IS_ALIGNED(end - start + 1, fs_info->nodesize)) {
605 WARN_ON(IS_ENABLED(CONFIG_BTRFS_DEBUG));
606 btrfs_err(fs_info, "invalid tree read bytenr");
607 return -EUCLEAN;
608 }
609
610 /*
611 * We don't allow bio merge for subpage metadata read, so we should
612 * only get one eb for each endio hook.
613 */
614 ASSERT(end == start + fs_info->nodesize - 1);
615 ASSERT(PagePrivate(page));
616
617 rcu_read_lock();
618 eb = radix_tree_lookup(&fs_info->buffer_radix,
> 619 start / fs_info->sectorsize);
620 rcu_read_unlock();
621
622 /*
623 * When we are reading one tree block, eb must have been
624 * inserted into the radix tree. If not something is wrong.
625 */
626 if (!eb) {
627 WARN_ON(IS_ENABLED(CONFIG_BTRFS_DEBUG));
628 btrfs_err(fs_info,
629 "can't find extent buffer for bytenr %llu",
630 start);
631 return -EUCLEAN;
632 }
633 /*
634 * The pending IO might have been the only thing that kept
635 * this buffer in memory. Make sure we have a ref for all
636 * this other checks
637 */
638 atomic_inc(&eb->refs);
639
640 reads_done = atomic_dec_and_test(&eb->io_pages);
641 /* Subpage read must finish in page read */
642 ASSERT(reads_done);
643
644 eb->read_mirror = mirror;
645 if (test_bit(EXTENT_BUFFER_READ_ERR, &eb->bflags)) {
646 ret = -EIO;
647 goto err;
648 }
649 ret = validate_extent_buffer(eb);
650 if (ret < 0)
651 goto err;
652
653 if (test_and_clear_bit(EXTENT_BUFFER_READAHEAD, &eb->bflags))
654 btree_readahead_hook(eb, ret);
655
656 set_extent_buffer_uptodate(eb);
657
658 free_extent_buffer(eb);
659 return ret;
660 err:
661 /*
662 * our io error hook is going to dec the io pages
663 * again, we have to make sure it has something to
664 * decrement
665 */
666 atomic_inc(&eb->io_pages);
667 clear_extent_buffer_uptodate(eb);
668 free_extent_buffer(eb);
669 return ret;
670 }
671
---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org
On 10.12.20 г. 8:39 ч., Qu Wenruo wrote: > For subpage metadata validation check, there are some difference: > - Read must finish in one bvec > Since we're just reading one subpage range in one page, it should > never be split into two bios nor two bvecs. > > - How to grab the existing eb > Instead of grabbing eb using page->private, we have to go search radix > tree as we don't have any direct pointer at hand. > > Signed-off-by: Qu Wenruo <wqu@suse.com> > --- > fs/btrfs/disk-io.c | 82 ++++++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 82 insertions(+) > > diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c > index b6c03a8b0c72..adda76895058 100644 > --- a/fs/btrfs/disk-io.c > +++ b/fs/btrfs/disk-io.c > @@ -591,6 +591,84 @@ static int validate_extent_buffer(struct extent_buffer *eb) > return ret; > } > > +static int validate_subpage_buffer(struct page *page, u64 start, u64 end, > + int mirror) > +{ > + struct btrfs_fs_info *fs_info = btrfs_sb(page->mapping->host->i_sb); > + struct extent_buffer *eb; > + int reads_done; > + int ret = 0; > + > + if (!IS_ALIGNED(start, fs_info->sectorsize) || That's guaranteed by the allocator. > + !IS_ALIGNED(end - start + 1, fs_info->sectorsize) || That's guaranteed by the fact that nodesize is a multiple of sectorsize. > + !IS_ALIGNED(end - start + 1, fs_info->nodesize)) { And that's also guaranteed that the size of an eb is always a nodesize. Also aren't those checks already performed by the tree-checker during write? Just remove this as it adds noise. > + WARN_ON(IS_ENABLED(CONFIG_BTRFS_DEBUG));> + btrfs_err(fs_info, "invalid tree read bytenr"); > + return -EUCLEAN; > + } > + > + /* > + * We don't allow bio merge for subpage metadata read, so we should > + * only get one eb for each endio hook. > + */ > + ASSERT(end == start + fs_info->nodesize - 1); > + ASSERT(PagePrivate(page)); > + > + rcu_read_lock(); > + eb = radix_tree_lookup(&fs_info->buffer_radix, > + start / fs_info->sectorsize); This division op likely produces the kernel robot's warning. It could be written to use >> fs_info->sectorsize_bits. Furthermore this usage of radix tree + rcu without acquiring the refs is unsafe as per my explanation of, essentially, identical issue in patch 12 and our offline chat about it. > + rcu_read_unlock(); > + > + /* > + * When we are reading one tree block, eb must have been > + * inserted into the radix tree. If not something is wrong. > + */ > + if (!eb) { > + WARN_ON(IS_ENABLED(CONFIG_BTRFS_DEBUG)); > + btrfs_err(fs_info, > + "can't find extent buffer for bytenr %llu", > + start); > + return -EUCLEAN; > + } That's impossible to execute and such a failure will result in a crash so just remove this code. > + /* > + * The pending IO might have been the only thing that kept > + * this buffer in memory. Make sure we have a ref for all > + * this other checks > + */ > + atomic_inc(&eb->refs); > + > + reads_done = atomic_dec_and_test(&eb->io_pages); > + /* Subpage read must finish in page read */ > + ASSERT(reads_done); Just ASSERT(atomic_dec_and_test(&eb->io_pages)). Again, for subpage I think that's a bit much since it only has 1 page so it's guaranteed that it will always be true. > + > + eb->read_mirror = mirror; > + if (test_bit(EXTENT_BUFFER_READ_ERR, &eb->bflags)) { > + ret = -EIO; > + goto err; > + } > + ret = validate_extent_buffer(eb); > + if (ret < 0) > + goto err; > + > + if (test_and_clear_bit(EXTENT_BUFFER_READAHEAD, &eb->bflags)) > + btree_readahead_hook(eb, ret); > + > + set_extent_buffer_uptodate(eb); > + > + free_extent_buffer(eb); > + return ret; > +err: > + /* > + * our io error hook is going to dec the io pages > + * again, we have to make sure it has something to > + * decrement > + */ That comment is slightly ambiguous - it's not the io error hook that does the decrement but end_bio_extent_readpage. Just rewrite the comment to : "end_bio_extent_readpage decrements io_pages in case of error, make sure it has ...." > + atomic_inc(&eb->io_pages); > + clear_extent_buffer_uptodate(eb); > + free_extent_buffer(eb); > + return ret; > +} > + > int btrfs_validate_metadata_buffer(struct btrfs_io_bio *io_bio, > struct page *page, u64 start, u64 end, > int mirror) > @@ -600,6 +678,10 @@ int btrfs_validate_metadata_buffer(struct btrfs_io_bio *io_bio, > int reads_done; > > ASSERT(page->private); > + > + if (btrfs_sb(page->mapping->host->i_sb)->sectorsize < PAGE_SIZE) > + return validate_subpage_buffer(page, start, end, mirror); nit: validate_metadata_buffer is called in only once place so I'm wondering won't it make it more readable if this check is lifted to its sole caller so that when reading end_bio_extent_readpage it's apparent what's going on. Though it's apparent that the nesting in the caller will get somewhat unwieldy so won't be pressing hard for this. > + > eb = (struct extent_buffer *)page->private; > > >
On 2020/12/14 下午6:21, Nikolay Borisov wrote: > > > On 10.12.20 г. 8:39 ч., Qu Wenruo wrote: >> For subpage metadata validation check, there are some difference: >> - Read must finish in one bvec >> Since we're just reading one subpage range in one page, it should >> never be split into two bios nor two bvecs. >> >> - How to grab the existing eb >> Instead of grabbing eb using page->private, we have to go search radix >> tree as we don't have any direct pointer at hand. >> >> Signed-off-by: Qu Wenruo <wqu@suse.com> >> --- >> fs/btrfs/disk-io.c | 82 ++++++++++++++++++++++++++++++++++++++++++++++ >> 1 file changed, 82 insertions(+) >> >> diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c >> index b6c03a8b0c72..adda76895058 100644 >> --- a/fs/btrfs/disk-io.c >> +++ b/fs/btrfs/disk-io.c >> @@ -591,6 +591,84 @@ static int validate_extent_buffer(struct extent_buffer *eb) >> return ret; >> } >> >> +static int validate_subpage_buffer(struct page *page, u64 start, u64 end, >> + int mirror) >> +{ >> + struct btrfs_fs_info *fs_info = btrfs_sb(page->mapping->host->i_sb); >> + struct extent_buffer *eb; >> + int reads_done; >> + int ret = 0; >> + >> + if (!IS_ALIGNED(start, fs_info->sectorsize) || > > That's guaranteed by the allocator. > >> + !IS_ALIGNED(end - start + 1, fs_info->sectorsize) || > That's guaranteed by the fact that nodesize is a multiple of sectorsize. > >> + !IS_ALIGNED(end - start + 1, fs_info->nodesize)) { > > And that's also guaranteed that the size of an eb is always a nodesize. > Also aren't those checks already performed by the tree-checker during > write? Just remove this as it adds noise. > >> + WARN_ON(IS_ENABLED(CONFIG_BTRFS_DEBUG));> + btrfs_err(fs_info, "invalid tree read bytenr"); >> + return -EUCLEAN; >> + } >> + >> + /* >> + * We don't allow bio merge for subpage metadata read, so we should >> + * only get one eb for each endio hook. >> + */ >> + ASSERT(end == start + fs_info->nodesize - 1); >> + ASSERT(PagePrivate(page)); >> + >> + rcu_read_lock(); >> + eb = radix_tree_lookup(&fs_info->buffer_radix, >> + start / fs_info->sectorsize); > > This division op likely produces the kernel robot's warning. It could be > written to use >> fs_info->sectorsize_bits. Furthermore this usage of > radix tree + rcu without acquiring the refs is unsafe as per my > explanation of, essentially, identical issue in patch 12 and our offline > chat about it. Another relic I forgot in the long update history, nice find. > >> + rcu_read_unlock(); >> + >> + /* >> + * When we are reading one tree block, eb must have been >> + * inserted into the radix tree. If not something is wrong. >> + */ >> + if (!eb) { >> + WARN_ON(IS_ENABLED(CONFIG_BTRFS_DEBUG)); >> + btrfs_err(fs_info, >> + "can't find extent buffer for bytenr %llu", >> + start); >> + return -EUCLEAN; >> + } > > That's impossible to execute and such a failure will result in a crash > so just remove this code. > >> + /* >> + * The pending IO might have been the only thing that kept >> + * this buffer in memory. Make sure we have a ref for all >> + * this other checks >> + */ >> + atomic_inc(&eb->refs); >> + >> + reads_done = atomic_dec_and_test(&eb->io_pages); >> + /* Subpage read must finish in page read */ >> + ASSERT(reads_done); > > Just ASSERT(atomic_dec_and_test(&eb->io_pages)). Again, for subpage I > think that's a bit much since it only has 1 page so it's guaranteed that > it will always be true. IIRC ASSERT() won't execute whatever in it for non debug build. Thus ASSERT(atomic_*) would cause non-debug kernel not to decrease the io_pages and hangs the system. Exactly the pitfall I'm thinking of. Thanks, Qu >> + >> + eb->read_mirror = mirror; >> + if (test_bit(EXTENT_BUFFER_READ_ERR, &eb->bflags)) { >> + ret = -EIO; >> + goto err; >> + } >> + ret = validate_extent_buffer(eb); >> + if (ret < 0) >> + goto err; >> + >> + if (test_and_clear_bit(EXTENT_BUFFER_READAHEAD, &eb->bflags)) >> + btree_readahead_hook(eb, ret); >> + >> + set_extent_buffer_uptodate(eb); >> + >> + free_extent_buffer(eb); >> + return ret; >> +err: >> + /* >> + * our io error hook is going to dec the io pages >> + * again, we have to make sure it has something to >> + * decrement >> + */ > > That comment is slightly ambiguous - it's not the io error hook that > does the decrement but end_bio_extent_readpage. Just rewrite the comment > to : > > "end_bio_extent_readpage decrements io_pages in case of error, make sure > it has ...." > >> + atomic_inc(&eb->io_pages); >> + clear_extent_buffer_uptodate(eb); >> + free_extent_buffer(eb); >> + return ret; >> +} >> + >> int btrfs_validate_metadata_buffer(struct btrfs_io_bio *io_bio, >> struct page *page, u64 start, u64 end, >> int mirror) >> @@ -600,6 +678,10 @@ int btrfs_validate_metadata_buffer(struct btrfs_io_bio *io_bio, >> int reads_done; >> >> ASSERT(page->private); >> + >> + if (btrfs_sb(page->mapping->host->i_sb)->sectorsize < PAGE_SIZE) >> + return validate_subpage_buffer(page, start, end, mirror); > > nit: validate_metadata_buffer is called in only once place so I'm > wondering won't it make it more readable if this check is lifted to its > sole caller so that when reading end_bio_extent_readpage it's apparent > what's going on. Though it's apparent that the nesting in the caller > will get somewhat unwieldy so won't be pressing hard for this. >> + >> eb = (struct extent_buffer *)page->private; >> >> >>
On 14.12.20 г. 12:50 ч., Qu Wenruo wrote: > > IIRC ASSERT() won't execute whatever in it for non debug build. > Thus ASSERT(atomic_*) would cause non-debug kernel not to decrease the > io_pages and hangs the system. Nope: 3362 #ifdef CONFIG_BTRFS_ASSERT 1 __cold __noreturn 2 static inline void assertfail(const char *expr, const char *file, int line) 3 { 4 pr_err("assertion failed: %s, in %s:%d\n", expr, file, line); 5 BUG(); 6 } 7 8 #define ASSERT(expr) \ 9 (likely(expr) ? (void)0 : assertfail(#expr, __FILE__, __LINE__)) 10 11 #else 12 static inline void assertfail(const char *expr, const char* file, int line) { } 13 #define ASSERT(expr) (void)(expr) <-- expression is evaluated. 14 #endif
On 2020/12/14 下午7:17, Nikolay Borisov wrote: > > > On 14.12.20 г. 12:50 ч., Qu Wenruo wrote: >> >> IIRC ASSERT() won't execute whatever in it for non debug build. >> Thus ASSERT(atomic_*) would cause non-debug kernel not to decrease the >> io_pages and hangs the system. > > Nope: > > 3362 #ifdef CONFIG_BTRFS_ASSERT > 1 __cold __noreturn > 2 static inline void assertfail(const char *expr, const char *file, int line) > 3 { > 4 pr_err("assertion failed: %s, in %s:%d\n", expr, file, line); > 5 BUG(); > 6 } > 7 > 8 #define ASSERT(expr) \ > 9 (likely(expr) ? (void)0 : assertfail(#expr, __FILE__, __LINE__)) > 10 > 11 #else > 12 static inline void assertfail(const char *expr, const char* file, int line) { } > 13 #define ASSERT(expr) (void)(expr) <-- expression is evaluated. > 14 #endif > Wow, that's too tricky and maybe that's the reason why Josef is complaining about the ASSERT()s slows down the system. In fact, from the assert(3) man page, we're doing things differently than user space at least: If the macro NDEBUG is defined at the moment <assert.h> was last included, the macro assert() generates no code, and hence does nothing at all. So I'm confused, what's the proper way to do ASSERT()? Thanks, Qu
On 14.12.20 г. 13:32 ч., Qu Wenruo wrote: > > > On 2020/12/14 下午7:17, Nikolay Borisov wrote: >> >> >> On 14.12.20 г. 12:50 ч., Qu Wenruo wrote: >>> >>> IIRC ASSERT() won't execute whatever in it for non debug build. >>> Thus ASSERT(atomic_*) would cause non-debug kernel not to decrease the >>> io_pages and hangs the system. >> >> Nope: >> >> 3362 #ifdef CONFIG_BTRFS_ASSERT >> 1 __cold __noreturn >> 2 static inline void assertfail(const char *expr, const char >> *file, int line) >> 3 { >> 4 pr_err("assertion failed: %s, in %s:%d\n", expr, file, >> line); >> 5 BUG(); >> 6 } >> 7 >> 8 #define ASSERT(expr) \ >> 9 (likely(expr) ? (void)0 : assertfail(#expr, __FILE__, >> __LINE__)) >> 10 >> 11 #else >> 12 static inline void assertfail(const char *expr, const char* >> file, int line) { } >> 13 #define ASSERT(expr) (void)(expr) <-- >> expression is evaluated. >> 14 #endif >> > Wow, that's too tricky and maybe that's the reason why Josef is > complaining about the ASSERT()s slows down the system. > > In fact, from the assert(3) man page, we're doing things differently > than user space at least: > > If the macro NDEBUG is defined at the moment <assert.h> was last > included, the macro assert() generates no code, and hence does nothing > at all. > > So I'm confused, what's the proper way to do ASSERT()? Well as it stands now, what I suggested would work. OTOH this really puts forward the question why do we leave code around (well, the compiler should really eliminate those redundant checks). Hm, David? > > Thanks, > Qu >
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index b6c03a8b0c72..adda76895058 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -591,6 +591,84 @@ static int validate_extent_buffer(struct extent_buffer *eb) return ret; } +static int validate_subpage_buffer(struct page *page, u64 start, u64 end, + int mirror) +{ + struct btrfs_fs_info *fs_info = btrfs_sb(page->mapping->host->i_sb); + struct extent_buffer *eb; + int reads_done; + int ret = 0; + + if (!IS_ALIGNED(start, fs_info->sectorsize) || + !IS_ALIGNED(end - start + 1, fs_info->sectorsize) || + !IS_ALIGNED(end - start + 1, fs_info->nodesize)) { + WARN_ON(IS_ENABLED(CONFIG_BTRFS_DEBUG)); + btrfs_err(fs_info, "invalid tree read bytenr"); + return -EUCLEAN; + } + + /* + * We don't allow bio merge for subpage metadata read, so we should + * only get one eb for each endio hook. + */ + ASSERT(end == start + fs_info->nodesize - 1); + ASSERT(PagePrivate(page)); + + rcu_read_lock(); + eb = radix_tree_lookup(&fs_info->buffer_radix, + start / fs_info->sectorsize); + rcu_read_unlock(); + + /* + * When we are reading one tree block, eb must have been + * inserted into the radix tree. If not something is wrong. + */ + if (!eb) { + WARN_ON(IS_ENABLED(CONFIG_BTRFS_DEBUG)); + btrfs_err(fs_info, + "can't find extent buffer for bytenr %llu", + start); + return -EUCLEAN; + } + /* + * The pending IO might have been the only thing that kept + * this buffer in memory. Make sure we have a ref for all + * this other checks + */ + atomic_inc(&eb->refs); + + reads_done = atomic_dec_and_test(&eb->io_pages); + /* Subpage read must finish in page read */ + ASSERT(reads_done); + + eb->read_mirror = mirror; + if (test_bit(EXTENT_BUFFER_READ_ERR, &eb->bflags)) { + ret = -EIO; + goto err; + } + ret = validate_extent_buffer(eb); + if (ret < 0) + goto err; + + if (test_and_clear_bit(EXTENT_BUFFER_READAHEAD, &eb->bflags)) + btree_readahead_hook(eb, ret); + + set_extent_buffer_uptodate(eb); + + free_extent_buffer(eb); + return ret; +err: + /* + * our io error hook is going to dec the io pages + * again, we have to make sure it has something to + * decrement + */ + atomic_inc(&eb->io_pages); + clear_extent_buffer_uptodate(eb); + free_extent_buffer(eb); + return ret; +} + int btrfs_validate_metadata_buffer(struct btrfs_io_bio *io_bio, struct page *page, u64 start, u64 end, int mirror) @@ -600,6 +678,10 @@ int btrfs_validate_metadata_buffer(struct btrfs_io_bio *io_bio, int reads_done; ASSERT(page->private); + + if (btrfs_sb(page->mapping->host->i_sb)->sectorsize < PAGE_SIZE) + return validate_subpage_buffer(page, start, end, mirror); + eb = (struct extent_buffer *)page->private;
For subpage metadata validation check, there are some difference: - Read must finish in one bvec Since we're just reading one subpage range in one page, it should never be split into two bios nor two bvecs. - How to grab the existing eb Instead of grabbing eb using page->private, we have to go search radix tree as we don't have any direct pointer at hand. Signed-off-by: Qu Wenruo <wqu@suse.com> --- fs/btrfs/disk-io.c | 82 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 82 insertions(+)