* [f2fs-dev] [PATCH v3] f2fs: avoid splitting bio when reading multiple pages @ 2025-06-25 6:49 Jianan Huang via Linux-f2fs-devel 2025-06-25 8:45 ` Chao Yu via Linux-f2fs-devel 0 siblings, 1 reply; 6+ messages in thread From: Jianan Huang via Linux-f2fs-devel @ 2025-06-25 6:49 UTC (permalink / raw) To: linux-f2fs-devel, chao, jaegeuk; +Cc: Sheng Yong, linux-kernel, wanghui33 When fewer pages are read, nr_pages may be smaller than nr_cpages. Due to the nr_vecs limit, the compressed pages will be split into multiple bios and then merged at the block level. In this case, nr_cpages should be used to pre-allocate bvecs. To handle this case, align max_nr_pages to cluster_size, which should be enough for all compressed pages. Signed-off-by: Jianan Huang <huangjianan@xiaomi.com> Signed-off-by: Sheng Yong <shengyong1@xiaomi.com> --- Changes since v2: - Initialize index only for compressed files. Changes since v1: - Use aligned nr_pages instead of nr_cpages to pre-allocate bvecs. fs/f2fs/data.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c index 31e892842625..d071d9f6a811 100644 --- a/fs/f2fs/data.c +++ b/fs/f2fs/data.c @@ -2303,7 +2303,7 @@ int f2fs_read_multi_pages(struct compress_ctx *cc, struct bio **bio_ret, } if (!bio) { - bio = f2fs_grab_read_bio(inode, blkaddr, nr_pages, + bio = f2fs_grab_read_bio(inode, blkaddr, nr_pages - i, f2fs_ra_op_flags(rac), folio->index, for_write); if (IS_ERR(bio)) { @@ -2376,6 +2376,14 @@ static int f2fs_mpage_readpages(struct inode *inode, unsigned max_nr_pages = nr_pages; int ret = 0; +#ifdef CONFIG_F2FS_FS_COMPRESSION + if (f2fs_compressed_file(inode)) { + index = rac ? readahead_index(rac) : folio->index; + max_nr_pages = round_up(index + nr_pages, cc.cluster_size) - + round_down(index, cc.cluster_size); + } +#endif + map.m_pblk = 0; map.m_lblk = 0; map.m_len = 0; @@ -2385,7 +2393,7 @@ static int f2fs_mpage_readpages(struct inode *inode, map.m_seg_type = NO_CHECK_TYPE; map.m_may_create = false; - for (; nr_pages; nr_pages--) { + for (; nr_pages; nr_pages--, max_nr_pages--) { if (rac) { folio = readahead_folio(rac); prefetchw(&folio->flags); -- 2.43.0 _______________________________________________ Linux-f2fs-devel mailing list Linux-f2fs-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel ^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [f2fs-dev] [PATCH v3] f2fs: avoid splitting bio when reading multiple pages 2025-06-25 6:49 [f2fs-dev] [PATCH v3] f2fs: avoid splitting bio when reading multiple pages Jianan Huang via Linux-f2fs-devel @ 2025-06-25 8:45 ` Chao Yu via Linux-f2fs-devel 2025-06-25 9:48 ` [f2fs-dev] [External Mail]Re: " Huang Jianan via Linux-f2fs-devel 0 siblings, 1 reply; 6+ messages in thread From: Chao Yu via Linux-f2fs-devel @ 2025-06-25 8:45 UTC (permalink / raw) To: Jianan Huang, linux-f2fs-devel, jaegeuk Cc: Sheng Yong, linux-kernel, wanghui33 On 6/25/25 14:49, Jianan Huang wrote: > When fewer pages are read, nr_pages may be smaller than nr_cpages. Due > to the nr_vecs limit, the compressed pages will be split into multiple > bios and then merged at the block level. In this case, nr_cpages should > be used to pre-allocate bvecs. > To handle this case, align max_nr_pages to cluster_size, which should be > enough for all compressed pages. > > Signed-off-by: Jianan Huang <huangjianan@xiaomi.com> > Signed-off-by: Sheng Yong <shengyong1@xiaomi.com> > --- > Changes since v2: > - Initialize index only for compressed files. > Changes since v1: > - Use aligned nr_pages instead of nr_cpages to pre-allocate bvecs. > > fs/f2fs/data.c | 12 ++++++++++-- > 1 file changed, 10 insertions(+), 2 deletions(-) > > diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c > index 31e892842625..d071d9f6a811 100644 > --- a/fs/f2fs/data.c > +++ b/fs/f2fs/data.c > @@ -2303,7 +2303,7 @@ int f2fs_read_multi_pages(struct compress_ctx *cc, struct bio **bio_ret, > } > > if (!bio) { > - bio = f2fs_grab_read_bio(inode, blkaddr, nr_pages, > + bio = f2fs_grab_read_bio(inode, blkaddr, nr_pages - i, Jianan, Another case: read page #0,1,2,3 from block #1000,1001,1002, cluster_size=4. nr_pages=4 max_nr_pages=round_up(0+4,4)-round_down(0,4)=4 f2fs_mpage_readpages() calls f2fs_read_multi_pages() when nr_pages=1, at that time, max_nr_pages equals to 1 as well. f2fs_grab_read_bio(..., 1 - 0,...) allocate bio w/ 1 vec capacity, however, we need at least 3 vecs to merge all cpages, right? Thanks, > f2fs_ra_op_flags(rac), > folio->index, for_write); > if (IS_ERR(bio)) { > @@ -2376,6 +2376,14 @@ static int f2fs_mpage_readpages(struct inode *inode, > unsigned max_nr_pages = nr_pages; > int ret = 0; > > +#ifdef CONFIG_F2FS_FS_COMPRESSION > + if (f2fs_compressed_file(inode)) { > + index = rac ? readahead_index(rac) : folio->index; > + max_nr_pages = round_up(index + nr_pages, cc.cluster_size) - > + round_down(index, cc.cluster_size); > + } > +#endif > + > map.m_pblk = 0; > map.m_lblk = 0; > map.m_len = 0; > @@ -2385,7 +2393,7 @@ static int f2fs_mpage_readpages(struct inode *inode, > map.m_seg_type = NO_CHECK_TYPE; > map.m_may_create = false; > > - for (; nr_pages; nr_pages--) { > + for (; nr_pages; nr_pages--, max_nr_pages--) { > if (rac) { > folio = readahead_folio(rac); > prefetchw(&folio->flags); _______________________________________________ Linux-f2fs-devel mailing list Linux-f2fs-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [f2fs-dev] [External Mail]Re: [PATCH v3] f2fs: avoid splitting bio when reading multiple pages 2025-06-25 8:45 ` Chao Yu via Linux-f2fs-devel @ 2025-06-25 9:48 ` Huang Jianan via Linux-f2fs-devel 2025-06-25 9:50 ` Huang Jianan via Linux-f2fs-devel 0 siblings, 1 reply; 6+ messages in thread From: Huang Jianan via Linux-f2fs-devel @ 2025-06-25 9:48 UTC (permalink / raw) To: Chao Yu, linux-f2fs-devel@lists.sourceforge.net, jaegeuk@kernel.org Cc: 盛勇, linux-kernel@vger.kernel.org, 王辉 On 2025/6/25 16:45, Chao Yu wrote: > > On 6/25/25 14:49, Jianan Huang wrote: >> When fewer pages are read, nr_pages may be smaller than nr_cpages. Due >> to the nr_vecs limit, the compressed pages will be split into multiple >> bios and then merged at the block level. In this case, nr_cpages should >> be used to pre-allocate bvecs. >> To handle this case, align max_nr_pages to cluster_size, which should be >> enough for all compressed pages. >> >> Signed-off-by: Jianan Huang <huangjianan@xiaomi.com> >> Signed-off-by: Sheng Yong <shengyong1@xiaomi.com> >> --- >> Changes since v2: >> - Initialize index only for compressed files. >> Changes since v1: >> - Use aligned nr_pages instead of nr_cpages to pre-allocate bvecs. >> >> fs/f2fs/data.c | 12 ++++++++++-- >> 1 file changed, 10 insertions(+), 2 deletions(-) >> >> diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c >> index 31e892842625..d071d9f6a811 100644 >> --- a/fs/f2fs/data.c >> +++ b/fs/f2fs/data.c >> @@ -2303,7 +2303,7 @@ int f2fs_read_multi_pages(struct compress_ctx *cc, struct bio **bio_ret, >> } >> >> if (!bio) { >> - bio = f2fs_grab_read_bio(inode, blkaddr, nr_pages, >> + bio = f2fs_grab_read_bio(inode, blkaddr, nr_pages - i, > > Jianan, > > Another case: > > read page #0,1,2,3 from block #1000,1001,1002, cluster_size=4. > > nr_pages=4 > max_nr_pages=round_up(0+4,4)-round_down(0,4)=4 > > f2fs_mpage_readpages() calls f2fs_read_multi_pages() when nr_pages=1, at > that time, max_nr_pages equals to 1 as well. > > f2fs_grab_read_bio(..., 1 - 0,...) allocate bio w/ 1 vec capacity, however, > we need at least 3 vecs to merge all cpages, right? > Hi, chao, If we don't align nr_pages, then when entering f2fs_read_multi_pages, we have nr_pages pages left, which belong to other clusters. If this is the last page, we can simply pass nr_pages = 0. When allocating bio, we need: 1. The cpages remaining in the current cluster, which should be (nr_capges - i). 2. The maximum cpages remaining in other clusters, which should be max(nr_pages, cc->nr_cpages). So (nr_capges - i) + max(nr_pages, nr_cpages), should be enough for all vecs? Thanks, > Thanks, > >> f2fs_ra_op_flags(rac), >> folio->index, for_write); >> if (IS_ERR(bio)) { >> @@ -2376,6 +2376,14 @@ static int f2fs_mpage_readpages(struct inode *inode, >> unsigned max_nr_pages = nr_pages; >> int ret = 0; >> >> +#ifdef CONFIG_F2FS_FS_COMPRESSION >> + if (f2fs_compressed_file(inode)) { >> + index = rac ? readahead_index(rac) : folio->index; >> + max_nr_pages = round_up(index + nr_pages, cc.cluster_size) - >> + round_down(index, cc.cluster_size); >> + } >> +#endif >> + >> map.m_pblk = 0; >> map.m_lblk = 0; >> map.m_len = 0; >> @@ -2385,7 +2393,7 @@ static int f2fs_mpage_readpages(struct inode *inode, >> map.m_seg_type = NO_CHECK_TYPE; >> map.m_may_create = false; >> >> - for (; nr_pages; nr_pages--) { >> + for (; nr_pages; nr_pages--, max_nr_pages--) { >> if (rac) { >> folio = readahead_folio(rac); >> prefetchw(&folio->flags); > _______________________________________________ Linux-f2fs-devel mailing list Linux-f2fs-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [f2fs-dev] [External Mail]Re: [PATCH v3] f2fs: avoid splitting bio when reading multiple pages 2025-06-25 9:48 ` [f2fs-dev] [External Mail]Re: " Huang Jianan via Linux-f2fs-devel @ 2025-06-25 9:50 ` Huang Jianan via Linux-f2fs-devel 2025-06-30 11:23 ` Chao Yu via Linux-f2fs-devel 0 siblings, 1 reply; 6+ messages in thread From: Huang Jianan via Linux-f2fs-devel @ 2025-06-25 9:50 UTC (permalink / raw) To: Chao Yu, linux-f2fs-devel@lists.sourceforge.net, jaegeuk@kernel.org Cc: 盛勇, linux-kernel@vger.kernel.org, 王辉 On 2025/6/25 17:48, Jianan Huang wrote: > On 2025/6/25 16:45, Chao Yu wrote: >> >> On 6/25/25 14:49, Jianan Huang wrote: >>> When fewer pages are read, nr_pages may be smaller than nr_cpages. Due >>> to the nr_vecs limit, the compressed pages will be split into multiple >>> bios and then merged at the block level. In this case, nr_cpages should >>> be used to pre-allocate bvecs. >>> To handle this case, align max_nr_pages to cluster_size, which should be >>> enough for all compressed pages. >>> >>> Signed-off-by: Jianan Huang <huangjianan@xiaomi.com> >>> Signed-off-by: Sheng Yong <shengyong1@xiaomi.com> >>> --- >>> Changes since v2: >>> - Initialize index only for compressed files. >>> Changes since v1: >>> - Use aligned nr_pages instead of nr_cpages to pre-allocate bvecs. >>> >>> fs/f2fs/data.c | 12 ++++++++++-- >>> 1 file changed, 10 insertions(+), 2 deletions(-) >>> >>> diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c >>> index 31e892842625..d071d9f6a811 100644 >>> --- a/fs/f2fs/data.c >>> +++ b/fs/f2fs/data.c >>> @@ -2303,7 +2303,7 @@ int f2fs_read_multi_pages(struct compress_ctx >>> *cc, struct bio **bio_ret, >>> } >>> >>> if (!bio) { >>> - bio = f2fs_grab_read_bio(inode, blkaddr, nr_pages, >>> + bio = f2fs_grab_read_bio(inode, blkaddr, >>> nr_pages - i, >> >> Jianan, >> >> Another case: >> >> read page #0,1,2,3 from block #1000,1001,1002, cluster_size=4. >> >> nr_pages=4 >> max_nr_pages=round_up(0+4,4)-round_down(0,4)=4 >> >> f2fs_mpage_readpages() calls f2fs_read_multi_pages() when nr_pages=1, at >> that time, max_nr_pages equals to 1 as well. >> >> f2fs_grab_read_bio(..., 1 - 0,...) allocate bio w/ 1 vec capacity, >> however, >> we need at least 3 vecs to merge all cpages, right? >> > > Hi, chao, > > If we don't align nr_pages, then when entering f2fs_read_multi_pages, > we have nr_pages pages left, which belong to other clusters. > If this is the last page, we can simply pass nr_pages = 0. > > When allocating bio, we need: > 1. The cpages remaining in the current cluster, which should be > (nr_capges - i). > 2. The maximum cpages remaining in other clusters, which should be > max(nr_pages, cc->nr_cpages). > align(nr_pages, cc->nr_cpages), sorry for this. > So (nr_capges - i) + max(nr_pages, nr_cpages), should be enough for all > vecs? > > Thanks, > > >> Thanks, >> >>> f2fs_ra_op_flags(rac), >>> folio->index, for_write); >>> if (IS_ERR(bio)) { >>> @@ -2376,6 +2376,14 @@ static int f2fs_mpage_readpages(struct inode >>> *inode, >>> unsigned max_nr_pages = nr_pages; >>> int ret = 0; >>> >>> +#ifdef CONFIG_F2FS_FS_COMPRESSION >>> + if (f2fs_compressed_file(inode)) { >>> + index = rac ? readahead_index(rac) : folio->index; >>> + max_nr_pages = round_up(index + nr_pages, >>> cc.cluster_size) - >>> + round_down(index, cc.cluster_size); >>> + } >>> +#endif >>> + >>> map.m_pblk = 0; >>> map.m_lblk = 0; >>> map.m_len = 0; >>> @@ -2385,7 +2393,7 @@ static int f2fs_mpage_readpages(struct inode >>> *inode, >>> map.m_seg_type = NO_CHECK_TYPE; >>> map.m_may_create = false; >>> >>> - for (; nr_pages; nr_pages--) { >>> + for (; nr_pages; nr_pages--, max_nr_pages--) { >>> if (rac) { >>> folio = readahead_folio(rac); >>> prefetchw(&folio->flags); >> > _______________________________________________ Linux-f2fs-devel mailing list Linux-f2fs-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [f2fs-dev] [External Mail]Re: [PATCH v3] f2fs: avoid splitting bio when reading multiple pages 2025-06-25 9:50 ` Huang Jianan via Linux-f2fs-devel @ 2025-06-30 11:23 ` Chao Yu via Linux-f2fs-devel 2025-06-30 12:58 ` Huang Jianan via Linux-f2fs-devel 0 siblings, 1 reply; 6+ messages in thread From: Chao Yu via Linux-f2fs-devel @ 2025-06-30 11:23 UTC (permalink / raw) To: Huang Jianan, linux-f2fs-devel@lists.sourceforge.net, jaegeuk@kernel.org Cc: 盛勇, linux-kernel@vger.kernel.org, 王辉 On 6/25/25 17:50, Huang Jianan wrote: > On 2025/6/25 17:48, Jianan Huang wrote: >> On 2025/6/25 16:45, Chao Yu wrote: >>> >>> On 6/25/25 14:49, Jianan Huang wrote: >>>> When fewer pages are read, nr_pages may be smaller than nr_cpages. Due >>>> to the nr_vecs limit, the compressed pages will be split into multiple >>>> bios and then merged at the block level. In this case, nr_cpages should >>>> be used to pre-allocate bvecs. >>>> To handle this case, align max_nr_pages to cluster_size, which should be >>>> enough for all compressed pages. >>>> >>>> Signed-off-by: Jianan Huang <huangjianan@xiaomi.com> >>>> Signed-off-by: Sheng Yong <shengyong1@xiaomi.com> >>>> --- >>>> Changes since v2: >>>> - Initialize index only for compressed files. >>>> Changes since v1: >>>> - Use aligned nr_pages instead of nr_cpages to pre-allocate bvecs. >>>> >>>> fs/f2fs/data.c | 12 ++++++++++-- >>>> 1 file changed, 10 insertions(+), 2 deletions(-) >>>> >>>> diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c >>>> index 31e892842625..d071d9f6a811 100644 >>>> --- a/fs/f2fs/data.c >>>> +++ b/fs/f2fs/data.c >>>> @@ -2303,7 +2303,7 @@ int f2fs_read_multi_pages(struct compress_ctx >>>> *cc, struct bio **bio_ret, >>>> } >>>> >>>> if (!bio) { >>>> - bio = f2fs_grab_read_bio(inode, blkaddr, nr_pages, >>>> + bio = f2fs_grab_read_bio(inode, blkaddr, >>>> nr_pages - i, >>> >>> Jianan, >>> >>> Another case: >>> >>> read page #0,1,2,3 from block #1000,1001,1002, cluster_size=4. >>> >>> nr_pages=4 >>> max_nr_pages=round_up(0+4,4)-round_down(0,4)=4 >>> >>> f2fs_mpage_readpages() calls f2fs_read_multi_pages() when nr_pages=1, at >>> that time, max_nr_pages equals to 1 as well. >>> >>> f2fs_grab_read_bio(..., 1 - 0,...) allocate bio w/ 1 vec capacity, >>> however, >>> we need at least 3 vecs to merge all cpages, right? >>> >> >> Hi, chao, >> >> If we don't align nr_pages, then when entering f2fs_read_multi_pages, >> we have nr_pages pages left, which belong to other clusters. >> If this is the last page, we can simply pass nr_pages = 0. >> >> When allocating bio, we need: >> 1. The cpages remaining in the current cluster, which should be >> (nr_capges - i). >> 2. The maximum cpages remaining in other clusters, which should be >> max(nr_pages, cc->nr_cpages). >> > > align(nr_pages, cc->nr_cpages), sorry for this. > >> So (nr_capges - i) + max(nr_pages, nr_cpages), should be enough for all >> vecs? Jianan, What about getting rid of below change? and just passing max_nr_pages to f2fs_read_multi_pages? Maybe there is a little bit waste for bio vector space, but it will be more safe to reserve enough margin. + for (; nr_pages; nr_pages--, max_nr_pages--) { Thanks, >> >> Thanks, >> >> >>> Thanks, >>> >>>> f2fs_ra_op_flags(rac), >>>> folio->index, for_write); >>>> if (IS_ERR(bio)) { >>>> @@ -2376,6 +2376,14 @@ static int f2fs_mpage_readpages(struct inode >>>> *inode, >>>> unsigned max_nr_pages = nr_pages; >>>> int ret = 0; >>>> >>>> +#ifdef CONFIG_F2FS_FS_COMPRESSION >>>> + if (f2fs_compressed_file(inode)) { >>>> + index = rac ? readahead_index(rac) : folio->index; >>>> + max_nr_pages = round_up(index + nr_pages, >>>> cc.cluster_size) - >>>> + round_down(index, cc.cluster_size); >>>> + } >>>> +#endif >>>> + >>>> map.m_pblk = 0; >>>> map.m_lblk = 0; >>>> map.m_len = 0; >>>> @@ -2385,7 +2393,7 @@ static int f2fs_mpage_readpages(struct inode >>>> *inode, >>>> map.m_seg_type = NO_CHECK_TYPE; >>>> map.m_may_create = false; >>>> >>>> - for (; nr_pages; nr_pages--) { >>>> + for (; nr_pages; nr_pages--, max_nr_pages--) { >>>> if (rac) { >>>> folio = readahead_folio(rac); >>>> prefetchw(&folio->flags); >>> >> > _______________________________________________ Linux-f2fs-devel mailing list Linux-f2fs-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [f2fs-dev] [External Mail]Re: [PATCH v3] f2fs: avoid splitting bio when reading multiple pages 2025-06-30 11:23 ` Chao Yu via Linux-f2fs-devel @ 2025-06-30 12:58 ` Huang Jianan via Linux-f2fs-devel 0 siblings, 0 replies; 6+ messages in thread From: Huang Jianan via Linux-f2fs-devel @ 2025-06-30 12:58 UTC (permalink / raw) To: Chao Yu, linux-f2fs-devel@lists.sourceforge.net, jaegeuk@kernel.org Cc: 盛勇, linux-kernel@vger.kernel.org, 王辉 On 2025/6/30 19:23, Chao Yu wrote: > > On 6/25/25 17:50, Huang Jianan wrote: >> On 2025/6/25 17:48, Jianan Huang wrote: >>> On 2025/6/25 16:45, Chao Yu wrote: >>>> >>>> On 6/25/25 14:49, Jianan Huang wrote: >>>>> When fewer pages are read, nr_pages may be smaller than nr_cpages. Due >>>>> to the nr_vecs limit, the compressed pages will be split into multiple >>>>> bios and then merged at the block level. In this case, nr_cpages should >>>>> be used to pre-allocate bvecs. >>>>> To handle this case, align max_nr_pages to cluster_size, which should be >>>>> enough for all compressed pages. >>>>> >>>>> Signed-off-by: Jianan Huang <huangjianan@xiaomi.com> >>>>> Signed-off-by: Sheng Yong <shengyong1@xiaomi.com> >>>>> --- >>>>> Changes since v2: >>>>> - Initialize index only for compressed files. >>>>> Changes since v1: >>>>> - Use aligned nr_pages instead of nr_cpages to pre-allocate bvecs. >>>>> >>>>> fs/f2fs/data.c | 12 ++++++++++-- >>>>> 1 file changed, 10 insertions(+), 2 deletions(-) >>>>> >>>>> diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c >>>>> index 31e892842625..d071d9f6a811 100644 >>>>> --- a/fs/f2fs/data.c >>>>> +++ b/fs/f2fs/data.c >>>>> @@ -2303,7 +2303,7 @@ int f2fs_read_multi_pages(struct compress_ctx >>>>> *cc, struct bio **bio_ret, >>>>> } >>>>> >>>>> if (!bio) { >>>>> - bio = f2fs_grab_read_bio(inode, blkaddr, nr_pages, >>>>> + bio = f2fs_grab_read_bio(inode, blkaddr, >>>>> nr_pages - i, >>>> >>>> Jianan, >>>> >>>> Another case: >>>> >>>> read page #0,1,2,3 from block #1000,1001,1002, cluster_size=4. >>>> >>>> nr_pages=4 >>>> max_nr_pages=round_up(0+4,4)-round_down(0,4)=4 >>>> >>>> f2fs_mpage_readpages() calls f2fs_read_multi_pages() when nr_pages=1, at >>>> that time, max_nr_pages equals to 1 as well. >>>> >>>> f2fs_grab_read_bio(..., 1 - 0,...) allocate bio w/ 1 vec capacity, >>>> however, >>>> we need at least 3 vecs to merge all cpages, right? >>>> >>> >>> Hi, chao, >>> >>> If we don't align nr_pages, then when entering f2fs_read_multi_pages, >>> we have nr_pages pages left, which belong to other clusters. >>> If this is the last page, we can simply pass nr_pages = 0. >>> >>> When allocating bio, we need: >>> 1. The cpages remaining in the current cluster, which should be >>> (nr_capges - i). >>> 2. The maximum cpages remaining in other clusters, which should be >>> max(nr_pages, cc->nr_cpages). >>> >> >> align(nr_pages, cc->nr_cpages), sorry for this. >> >>> So (nr_capges - i) + max(nr_pages, nr_cpages), should be enough for all >>> vecs? > > Jianan, > > What about getting rid of below change? and just passing max_nr_pages to > f2fs_read_multi_pages? Maybe there is a little bit waste for bio vector space, > but it will be more safe to reserve enough margin. > > + for (; nr_pages; nr_pages--, max_nr_pages--) { > LGTM, updated in v4. Thanks, > Thanks, > >>> >>> Thanks, >>> >>> >>>> Thanks, >>>> >>>>> f2fs_ra_op_flags(rac), >>>>> folio->index, for_write); >>>>> if (IS_ERR(bio)) { >>>>> @@ -2376,6 +2376,14 @@ static int f2fs_mpage_readpages(struct inode >>>>> *inode, >>>>> unsigned max_nr_pages = nr_pages; >>>>> int ret = 0; >>>>> >>>>> +#ifdef CONFIG_F2FS_FS_COMPRESSION >>>>> + if (f2fs_compressed_file(inode)) { >>>>> + index = rac ? readahead_index(rac) : folio->index; >>>>> + max_nr_pages = round_up(index + nr_pages, >>>>> cc.cluster_size) - >>>>> + round_down(index, cc.cluster_size); >>>>> + } >>>>> +#endif >>>>> + >>>>> map.m_pblk = 0; >>>>> map.m_lblk = 0; >>>>> map.m_len = 0; >>>>> @@ -2385,7 +2393,7 @@ static int f2fs_mpage_readpages(struct inode >>>>> *inode, >>>>> map.m_seg_type = NO_CHECK_TYPE; >>>>> map.m_may_create = false; >>>>> >>>>> - for (; nr_pages; nr_pages--) { >>>>> + for (; nr_pages; nr_pages--, max_nr_pages--) { >>>>> if (rac) { >>>>> folio = readahead_folio(rac); >>>>> prefetchw(&folio->flags); >>>> >>> >> > _______________________________________________ Linux-f2fs-devel mailing list Linux-f2fs-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel ^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2025-06-30 12:59 UTC | newest] Thread overview: 6+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2025-06-25 6:49 [f2fs-dev] [PATCH v3] f2fs: avoid splitting bio when reading multiple pages Jianan Huang via Linux-f2fs-devel 2025-06-25 8:45 ` Chao Yu via Linux-f2fs-devel 2025-06-25 9:48 ` [f2fs-dev] [External Mail]Re: " Huang Jianan via Linux-f2fs-devel 2025-06-25 9:50 ` Huang Jianan via Linux-f2fs-devel 2025-06-30 11:23 ` Chao Yu via Linux-f2fs-devel 2025-06-30 12:58 ` Huang Jianan via Linux-f2fs-devel
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