From: Qu Wenruo <quwenruo.btrfs@gmx.com>
To: Josef Bacik <josef@toxicpanda.com>, Qu Wenruo <wqu@suse.com>,
linux-btrfs@vger.kernel.org
Subject: Re: [PATCH v4 08/18] btrfs: introduce helper for subpage uptodate status
Date: Thu, 21 Jan 2021 08:49:30 +0800 [thread overview]
Message-ID: <3118cc60-2337-49da-648d-aa3b8cdcd70d@gmx.com> (raw)
In-Reply-To: <812a4f48-3210-926f-cf59-de63bfcc4c0d@toxicpanda.com>
On 2021/1/20 下午11:00, Josef Bacik wrote:
> On 1/16/21 2:15 AM, Qu Wenruo wrote:
>> This patch introduce the following functions to handle btrfs subpage
>> uptodate status:
>> - btrfs_subpage_set_uptodate()
>> - btrfs_subpage_clear_uptodate()
>> - btrfs_subpage_test_uptodate()
>> Those helpers can only be called when the range is ensured to be
>> inside the page.
>>
>> - btrfs_page_set_uptodate()
>> - btrfs_page_clear_uptodate()
>> - btrfs_page_test_uptodate()
>> Those helpers can handle both regular sector size and subpage without
>> problem.
>> Although caller should still ensure that the range is inside the page.
>>
>> Signed-off-by: Qu Wenruo <wqu@suse.com>
>> ---
>> fs/btrfs/subpage.h | 115 +++++++++++++++++++++++++++++++++++++++++++++
>> 1 file changed, 115 insertions(+)
>>
>> diff --git a/fs/btrfs/subpage.h b/fs/btrfs/subpage.h
>> index d8b34879368d..3373ef4ffec1 100644
>> --- a/fs/btrfs/subpage.h
>> +++ b/fs/btrfs/subpage.h
>> @@ -23,6 +23,7 @@
>> struct btrfs_subpage {
>> /* Common members for both data and metadata pages */
>> spinlock_t lock;
>> + u16 uptodate_bitmap;
>> union {
>> /* Structures only used by metadata */
>> bool under_alloc;
>> @@ -78,4 +79,118 @@ static inline void
>> btrfs_page_end_meta_alloc(struct btrfs_fs_info *fs_info,
>> int btrfs_attach_subpage(struct btrfs_fs_info *fs_info, struct page
>> *page);
>> void btrfs_detach_subpage(struct btrfs_fs_info *fs_info, struct page
>> *page);
>> +/*
>> + * Convert the [start, start + len) range into a u16 bitmap
>> + *
>> + * E.g. if start == page_offset() + 16K, len = 16K, we get 0x00f0.
>> + */
>> +static inline u16 btrfs_subpage_calc_bitmap(struct btrfs_fs_info
>> *fs_info,
>> + struct page *page, u64 start, u32 len)
>> +{
>> + int bit_start = offset_in_page(start) >> fs_info->sectorsize_bits;
>> + int nbits = len >> fs_info->sectorsize_bits;
>> +
>> + /* Basic checks */
>> + ASSERT(PagePrivate(page) && page->private);
>> + ASSERT(IS_ALIGNED(start, fs_info->sectorsize) &&
>> + IS_ALIGNED(len, fs_info->sectorsize));
>> +
>> + /*
>> + * The range check only works for mapped page, we can
>> + * still have unampped page like dummy extent buffer pages.
>> + */
>> + if (page->mapping)
>> + ASSERT(page_offset(page) <= start &&
>> + start + len <= page_offset(page) + PAGE_SIZE);
>> + /*
>> + * Here nbits can be 16, thus can go beyond u16 range. Here we
>> make the
>> + * first left shift to be calculated in unsigned long (u32), then
>> + * truncate the result to u16.
>> + */
>> + return (u16)(((1UL << nbits) - 1) << bit_start);
>> +}
>> +
>> +static inline void btrfs_subpage_set_uptodate(struct btrfs_fs_info
>> *fs_info,
>> + struct page *page, u64 start, u32 len)
>> +{
>> + struct btrfs_subpage *subpage = (struct btrfs_subpage
>> *)page->private;
>> + u16 tmp = btrfs_subpage_calc_bitmap(fs_info, page, start, len);
>> + unsigned long flags;
>> +
>> + spin_lock_irqsave(&subpage->lock, flags);
>> + subpage->uptodate_bitmap |= tmp;
>> + if (subpage->uptodate_bitmap == U16_MAX)
>> + SetPageUptodate(page);
>> + spin_unlock_irqrestore(&subpage->lock, flags);
>> +}
>> +
>> +static inline void btrfs_subpage_clear_uptodate(struct btrfs_fs_info
>> *fs_info,
>> + struct page *page, u64 start, u32 len)
>> +{
>> + struct btrfs_subpage *subpage = (struct btrfs_subpage
>> *)page->private;
>> + u16 tmp = btrfs_subpage_calc_bitmap(fs_info, page, start, len);
>> + unsigned long flags;
>> +
>> + spin_lock_irqsave(&subpage->lock, flags);
>> + subpage->uptodate_bitmap &= ~tmp;
>> + ClearPageUptodate(page);
>> + spin_unlock_irqrestore(&subpage->lock, flags);
>> +}
>> +
>> +/*
>> + * Unlike set/clear which is dependent on each page status, for test
>> all bits
>> + * are tested in the same way.
>> + */
>> +#define DECLARE_BTRFS_SUBPAGE_TEST_OP(name) \
>> +static inline bool btrfs_subpage_test_##name(struct btrfs_fs_info
>> *fs_info, \
>> + struct page *page, u64 start, u32 len) \
>> +{ \
>> + struct btrfs_subpage *subpage = (struct btrfs_subpage
>> *)page->private; \
>> + u16 tmp = btrfs_subpage_calc_bitmap(fs_info, page, start, len); \
>> + unsigned long flags; \
>> + bool ret; \
>> + \
>> + spin_lock_irqsave(&subpage->lock, flags); \
>> + ret = ((subpage->name##_bitmap & tmp) == tmp); \
>> + spin_unlock_irqrestore(&subpage->lock, flags); \
>> + return ret; \
>> +}
>> +DECLARE_BTRFS_SUBPAGE_TEST_OP(uptodate);
>> +
>> +/*
>> + * Note that, in selftest, especially extent-io-tests, we can have empty
>> + * fs_info passed in.
>> + * Thankfully in selftest, we only test sectorsize == PAGE_SIZE cases
>> so far,
>> + * thus we can fall back to regular sectorsize branch.
>> + */
>> +#define DECLARE_BTRFS_PAGE_OPS(name, set_page_func,
>> clear_page_func, \
>> + test_page_func) \
>> +static inline void btrfs_page_set_##name(struct btrfs_fs_info
>> *fs_info, \
>> + struct page *page, u64 start, u32 len) \
>> +{ \
>> + if (unlikely(!fs_info) || fs_info->sectorsize == PAGE_SIZE) { \
>> + set_page_func(page); \
>> + return; \
>> + } \
>> + btrfs_subpage_set_##name(fs_info, page, start, len); \
>> +} \
>> +static inline void btrfs_page_clear_##name(struct btrfs_fs_info
>> *fs_info, \
>> + struct page *page, u64 start, u32 len) \
>> +{ \
>> + if (unlikely(!fs_info) || fs_info->sectorsize == PAGE_SIZE) { \
>> + clear_page_func(page); \
>> + return; \
>> + } \
>> + btrfs_subpage_clear_##name(fs_info, page, start, len); \
>> +} \
>> +static inline bool btrfs_page_test_##name(struct btrfs_fs_info
>> *fs_info, \
>> + struct page *page, u64 start, u32 len) \
>> +{ \
>> + if (unlikely(!fs_info) || fs_info->sectorsize == PAGE_SIZE) \
>> + return test_page_func(page); \
>> + return btrfs_subpage_test_##name(fs_info, page, start, len); \
>> +}
>
> Another thing I just realized is you're doing this
>
> btrfs_page_set_uptodate(fs_info, page, eb->start, eb->len);
>
> but we default to a nodesize > PAGE_SIZE on x86. This is fine, because
> you're checking fs_info->sectorsize == PAGE_SIZE, which will mean we do
> the right thing.
>
> But what happens if fs_info->nodesize < PAGE_SIZE && fs_info->sectorsize
> == PAGE_SIZE? We by default have fs'es that ->nodesize != ->sectorsize,
> so really what we should be doing is checking if len == PAGE_SIZE here,
> but then you need to take into account the case that eb->len >
> PAGE_SIZE. Fix this to do the right thing in either of those cases.
> Thanks,
Impossible.
Nodesize must be >= sectorsize.
As sectorsize is currently the minimal access unit for both data and
metadata.
Thanks,
Qu
>
> Josef
next prev parent reply other threads:[~2021-01-21 5:26 UTC|newest]
Thread overview: 68+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-16 7:15 [PATCH v4 00/18] btrfs: add read-only support for subpage sector size Qu Wenruo
2021-01-16 7:15 ` [PATCH v4 01/18] btrfs: update locked page dirty/writeback/error bits in __process_pages_contig() Qu Wenruo
2021-01-19 21:41 ` Josef Bacik
2021-01-21 6:32 ` Qu Wenruo
2021-01-21 6:51 ` Qu Wenruo
2021-01-23 19:13 ` David Sterba
2021-01-24 0:35 ` Qu Wenruo
2021-01-24 11:49 ` David Sterba
2021-01-16 7:15 ` [PATCH v4 02/18] btrfs: merge PAGE_CLEAR_DIRTY and PAGE_SET_WRITEBACK into PAGE_START_WRITEBACK Qu Wenruo
2021-01-19 21:43 ` Josef Bacik
2021-01-19 21:45 ` Josef Bacik
2021-01-16 7:15 ` [PATCH v4 03/18] btrfs: introduce the skeleton of btrfs_subpage structure Qu Wenruo
2021-01-18 22:46 ` David Sterba
2021-01-18 22:54 ` Qu Wenruo
2021-01-19 15:51 ` David Sterba
2021-01-19 16:06 ` David Sterba
2021-01-20 0:19 ` Qu Wenruo
2021-01-23 19:37 ` David Sterba
2021-01-24 0:24 ` Qu Wenruo
2021-01-18 23:01 ` David Sterba
2021-01-16 7:15 ` [PATCH v4 04/18] btrfs: make attach_extent_buffer_page() to handle subpage case Qu Wenruo
2021-01-18 22:51 ` David Sterba
2021-01-19 21:54 ` Josef Bacik
2021-01-19 22:35 ` David Sterba
2021-01-26 7:29 ` Qu Wenruo
2021-01-27 19:58 ` David Sterba
2021-01-20 0:27 ` Qu Wenruo
2021-01-20 14:22 ` Josef Bacik
2021-01-21 1:20 ` Qu Wenruo
2021-01-16 7:15 ` [PATCH v4 05/18] btrfs: make grab_extent_buffer_from_page() " Qu Wenruo
2021-01-16 7:15 ` [PATCH v4 06/18] btrfs: support subpage for extent buffer page release Qu Wenruo
2021-01-20 14:44 ` Josef Bacik
2021-01-21 0:45 ` Qu Wenruo
2021-01-16 7:15 ` [PATCH v4 07/18] btrfs: attach private to dummy extent buffer pages Qu Wenruo
2021-01-20 14:48 ` Josef Bacik
2021-01-21 0:47 ` Qu Wenruo
2021-01-16 7:15 ` [PATCH v4 08/18] btrfs: introduce helper for subpage uptodate status Qu Wenruo
2021-01-19 19:45 ` David Sterba
2021-01-20 14:55 ` Josef Bacik
2021-01-26 7:21 ` Qu Wenruo
2021-01-20 15:00 ` Josef Bacik
2021-01-21 0:49 ` Qu Wenruo [this message]
2021-01-21 1:28 ` Josef Bacik
2021-01-21 1:38 ` Qu Wenruo
2021-01-16 7:15 ` [PATCH v4 09/18] btrfs: introduce helper for subpage error status Qu Wenruo
2021-01-16 7:15 ` [PATCH v4 10/18] btrfs: make set/clear_extent_buffer_uptodate() to support subpage size Qu Wenruo
2021-01-16 7:15 ` [PATCH v4 11/18] btrfs: make btrfs_clone_extent_buffer() to be subpage compatible Qu Wenruo
2021-01-16 7:15 ` [PATCH v4 12/18] btrfs: implement try_release_extent_buffer() for subpage metadata support Qu Wenruo
2021-01-20 15:05 ` Josef Bacik
2021-01-21 0:51 ` Qu Wenruo
2021-01-23 20:36 ` David Sterba
2021-01-25 20:02 ` Josef Bacik
2021-01-16 7:15 ` [PATCH v4 13/18] btrfs: introduce read_extent_buffer_subpage() Qu Wenruo
2021-01-20 15:08 ` Josef Bacik
2021-01-16 7:15 ` [PATCH v4 14/18] btrfs: extent_io: make endio_readpage_update_page_status() to handle subpage case Qu Wenruo
2021-01-16 7:15 ` [PATCH v4 15/18] btrfs: disk-io: introduce subpage metadata validation check Qu Wenruo
2021-01-16 7:15 ` [PATCH v4 16/18] btrfs: introduce btrfs_subpage for data inodes Qu Wenruo
2021-01-19 20:48 ` David Sterba
2021-01-20 15:28 ` Josef Bacik
2021-01-26 7:05 ` Qu Wenruo
2021-01-16 7:15 ` [PATCH v4 17/18] btrfs: integrate page status update for data read path into begin/end_page_read() Qu Wenruo
2021-01-20 15:41 ` Josef Bacik
2021-01-21 1:05 ` Qu Wenruo
2021-01-16 7:15 ` [PATCH v4 18/18] btrfs: allow RO mount of 4K sector size fs on 64K page system Qu Wenruo
2021-01-18 23:17 ` [PATCH v4 00/18] btrfs: add read-only support for subpage sector size David Sterba
2021-01-18 23:26 ` Qu Wenruo
2021-01-24 12:29 ` David Sterba
2021-01-25 1:19 ` Qu Wenruo
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