| Message ID | 20240213093713.1753368-6-kernel@pankajraghav.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | enable bs > ps in XFS | expand |
On 2/13/24 10:37, Pankaj Raghav (Samsung) wrote: > From: Luis Chamberlain <mcgrof@kernel.org> > > Align the ra->start and ra->size to mapping_min_order in > ondemand_readahead(), and align the index to mapping_min_order in > force_page_cache_ra(). This will ensure that the folios allocated for > readahead that are added to the page cache are aligned to > mapping_min_order. > > Signed-off-by: Luis Chamberlain <mcgrof@kernel.org> > Signed-off-by: Pankaj Raghav <p.raghav@samsung.com> > --- > mm/readahead.c | 48 ++++++++++++++++++++++++++++++++++++++++-------- > 1 file changed, 40 insertions(+), 8 deletions(-) > > diff --git a/mm/readahead.c b/mm/readahead.c > index 4fa7d0e65706..5e1ec7705c78 100644 > --- a/mm/readahead.c > +++ b/mm/readahead.c > @@ -315,6 +315,7 @@ void force_page_cache_ra(struct readahead_control *ractl, > struct file_ra_state *ra = ractl->ra; > struct backing_dev_info *bdi = inode_to_bdi(mapping->host); > unsigned long max_pages, index; > + unsigned int min_nrpages = mapping_min_folio_nrpages(mapping); > > if (unlikely(!mapping->a_ops->read_folio && !mapping->a_ops->readahead)) > return; > @@ -324,6 +325,13 @@ void force_page_cache_ra(struct readahead_control *ractl, > * be up to the optimal hardware IO size > */ > index = readahead_index(ractl); > + if (!IS_ALIGNED(index, min_nrpages)) { > + unsigned long old_index = index; > + > + index = round_down(index, min_nrpages); > + nr_to_read += (old_index - index); > + } > + > max_pages = max_t(unsigned long, bdi->io_pages, ra->ra_pages); > nr_to_read = min_t(unsigned long, nr_to_read, max_pages); > while (nr_to_read) { > @@ -332,6 +340,7 @@ void force_page_cache_ra(struct readahead_control *ractl, > if (this_chunk > nr_to_read) > this_chunk = nr_to_read; > ractl->_index = index; > + VM_BUG_ON(!IS_ALIGNED(index, min_nrpages)); > do_page_cache_ra(ractl, this_chunk, 0); > > index += this_chunk; > @@ -344,11 +353,20 @@ void force_page_cache_ra(struct readahead_control *ractl, > * for small size, x 4 for medium, and x 2 for large > * for 128k (32 page) max ra > * 1-2 page = 16k, 3-4 page 32k, 5-8 page = 64k, > 8 page = 128k initial > + * > + * For higher order address space requirements we ensure no initial reads > + * are ever less than the min number of pages required. > + * > + * We *always* cap the max io size allowed by the device. > */ > -static unsigned long get_init_ra_size(unsigned long size, unsigned long max) > +static unsigned long get_init_ra_size(unsigned long size, > + unsigned int min_nrpages, > + unsigned long max) > { > unsigned long newsize = roundup_pow_of_two(size); > > + newsize = max_t(unsigned long, newsize, min_nrpages); > + > if (newsize <= max / 32) > newsize = newsize * 4; > else if (newsize <= max / 4) > @@ -356,6 +374,8 @@ static unsigned long get_init_ra_size(unsigned long size, unsigned long max) > else > newsize = max; > > + VM_BUG_ON(newsize & (min_nrpages - 1)); > + > return newsize; > } > > @@ -364,14 +384,16 @@ static unsigned long get_init_ra_size(unsigned long size, unsigned long max) > * return it as the new window size. > */ > static unsigned long get_next_ra_size(struct file_ra_state *ra, > + unsigned int min_nrpages, > unsigned long max) > { > - unsigned long cur = ra->size; > + unsigned long cur = max(ra->size, min_nrpages); > > if (cur < max / 16) > return 4 * cur; > if (cur <= max / 2) > return 2 * cur; > + > return max; > } > > @@ -561,7 +583,11 @@ static void ondemand_readahead(struct readahead_control *ractl, > unsigned long add_pages; > pgoff_t index = readahead_index(ractl); > pgoff_t expected, prev_index; > - unsigned int order = folio ? folio_order(folio) : 0; > + unsigned int min_order = mapping_min_folio_order(ractl->mapping); > + unsigned int min_nrpages = mapping_min_folio_nrpages(ractl->mapping); > + unsigned int order = folio ? folio_order(folio) : min_order; > + > + VM_BUG_ON(!IS_ALIGNED(ractl->_index, min_nrpages)); > > /* > * If the request exceeds the readahead window, allow the read to > @@ -583,8 +609,8 @@ static void ondemand_readahead(struct readahead_control *ractl, > expected = round_down(ra->start + ra->size - ra->async_size, > 1UL << order); > if (index == expected || index == (ra->start + ra->size)) { > - ra->start += ra->size; > - ra->size = get_next_ra_size(ra, max_pages); > + ra->start += round_down(ra->size, min_nrpages); > + ra->size = get_next_ra_size(ra, min_nrpages, max_pages); > ra->async_size = ra->size; > goto readit; > } > @@ -603,13 +629,18 @@ static void ondemand_readahead(struct readahead_control *ractl, > max_pages); > rcu_read_unlock(); > > + start = round_down(start, min_nrpages); > + > + VM_BUG_ON(folio->index & (folio_nr_pages(folio) - 1)); > + > if (!start || start - index > max_pages) > return; > > ra->start = start; > ra->size = start - index; /* old async_size */ > + Stale whitespace. > ra->size += req_size; > - ra->size = get_next_ra_size(ra, max_pages); > + ra->size = get_next_ra_size(ra, min_nrpages, max_pages); > ra->async_size = ra->size; > goto readit; > } > @@ -646,7 +677,7 @@ static void ondemand_readahead(struct readahead_control *ractl, > > initial_readahead: > ra->start = index; > - ra->size = get_init_ra_size(req_size, max_pages); > + ra->size = get_init_ra_size(req_size, min_nrpages, max_pages); > ra->async_size = ra->size > req_size ? ra->size - req_size : ra->size; > > readit: > @@ -657,7 +688,7 @@ static void ondemand_readahead(struct readahead_control *ractl, > * Take care of maximum IO pages as above. > */ > if (index == ra->start && ra->size == ra->async_size) { > - add_pages = get_next_ra_size(ra, max_pages); > + add_pages = get_next_ra_size(ra, min_nrpages, max_pages); > if (ra->size + add_pages <= max_pages) { > ra->async_size = add_pages; > ra->size += add_pages; > @@ -668,6 +699,7 @@ static void ondemand_readahead(struct readahead_control *ractl, > } > > ractl->_index = ra->start; > + VM_BUG_ON(!IS_ALIGNED(ractl->_index, min_nrpages)); > page_cache_ra_order(ractl, ra, order); > } > Otherwise looks good. Cheers, Hannes
On Tue, Feb 13, 2024 at 10:37:04AM +0100, Pankaj Raghav (Samsung) wrote: > From: Luis Chamberlain <mcgrof@kernel.org> > > Align the ra->start and ra->size to mapping_min_order in > ondemand_readahead(), and align the index to mapping_min_order in > force_page_cache_ra(). This will ensure that the folios allocated for > readahead that are added to the page cache are aligned to > mapping_min_order. > > Signed-off-by: Luis Chamberlain <mcgrof@kernel.org> > Signed-off-by: Pankaj Raghav <p.raghav@samsung.com> Acked-by: Darrick J. Wong <djwong@kernel.org> --D > --- > mm/readahead.c | 48 ++++++++++++++++++++++++++++++++++++++++-------- > 1 file changed, 40 insertions(+), 8 deletions(-) > > diff --git a/mm/readahead.c b/mm/readahead.c > index 4fa7d0e65706..5e1ec7705c78 100644 > --- a/mm/readahead.c > +++ b/mm/readahead.c > @@ -315,6 +315,7 @@ void force_page_cache_ra(struct readahead_control *ractl, > struct file_ra_state *ra = ractl->ra; > struct backing_dev_info *bdi = inode_to_bdi(mapping->host); > unsigned long max_pages, index; > + unsigned int min_nrpages = mapping_min_folio_nrpages(mapping); > > if (unlikely(!mapping->a_ops->read_folio && !mapping->a_ops->readahead)) > return; > @@ -324,6 +325,13 @@ void force_page_cache_ra(struct readahead_control *ractl, > * be up to the optimal hardware IO size > */ > index = readahead_index(ractl); > + if (!IS_ALIGNED(index, min_nrpages)) { > + unsigned long old_index = index; > + > + index = round_down(index, min_nrpages); > + nr_to_read += (old_index - index); > + } > + > max_pages = max_t(unsigned long, bdi->io_pages, ra->ra_pages); > nr_to_read = min_t(unsigned long, nr_to_read, max_pages); > while (nr_to_read) { > @@ -332,6 +340,7 @@ void force_page_cache_ra(struct readahead_control *ractl, > if (this_chunk > nr_to_read) > this_chunk = nr_to_read; > ractl->_index = index; > + VM_BUG_ON(!IS_ALIGNED(index, min_nrpages)); > do_page_cache_ra(ractl, this_chunk, 0); > > index += this_chunk; > @@ -344,11 +353,20 @@ void force_page_cache_ra(struct readahead_control *ractl, > * for small size, x 4 for medium, and x 2 for large > * for 128k (32 page) max ra > * 1-2 page = 16k, 3-4 page 32k, 5-8 page = 64k, > 8 page = 128k initial > + * > + * For higher order address space requirements we ensure no initial reads > + * are ever less than the min number of pages required. > + * > + * We *always* cap the max io size allowed by the device. > */ > -static unsigned long get_init_ra_size(unsigned long size, unsigned long max) > +static unsigned long get_init_ra_size(unsigned long size, > + unsigned int min_nrpages, > + unsigned long max) > { > unsigned long newsize = roundup_pow_of_two(size); > > + newsize = max_t(unsigned long, newsize, min_nrpages); > + > if (newsize <= max / 32) > newsize = newsize * 4; > else if (newsize <= max / 4) > @@ -356,6 +374,8 @@ static unsigned long get_init_ra_size(unsigned long size, unsigned long max) > else > newsize = max; > > + VM_BUG_ON(newsize & (min_nrpages - 1)); > + > return newsize; > } > > @@ -364,14 +384,16 @@ static unsigned long get_init_ra_size(unsigned long size, unsigned long max) > * return it as the new window size. > */ > static unsigned long get_next_ra_size(struct file_ra_state *ra, > + unsigned int min_nrpages, > unsigned long max) > { > - unsigned long cur = ra->size; > + unsigned long cur = max(ra->size, min_nrpages); > > if (cur < max / 16) > return 4 * cur; > if (cur <= max / 2) > return 2 * cur; > + > return max; > } > > @@ -561,7 +583,11 @@ static void ondemand_readahead(struct readahead_control *ractl, > unsigned long add_pages; > pgoff_t index = readahead_index(ractl); > pgoff_t expected, prev_index; > - unsigned int order = folio ? folio_order(folio) : 0; > + unsigned int min_order = mapping_min_folio_order(ractl->mapping); > + unsigned int min_nrpages = mapping_min_folio_nrpages(ractl->mapping); > + unsigned int order = folio ? folio_order(folio) : min_order; > + > + VM_BUG_ON(!IS_ALIGNED(ractl->_index, min_nrpages)); > > /* > * If the request exceeds the readahead window, allow the read to > @@ -583,8 +609,8 @@ static void ondemand_readahead(struct readahead_control *ractl, > expected = round_down(ra->start + ra->size - ra->async_size, > 1UL << order); > if (index == expected || index == (ra->start + ra->size)) { > - ra->start += ra->size; > - ra->size = get_next_ra_size(ra, max_pages); > + ra->start += round_down(ra->size, min_nrpages); > + ra->size = get_next_ra_size(ra, min_nrpages, max_pages); > ra->async_size = ra->size; > goto readit; > } > @@ -603,13 +629,18 @@ static void ondemand_readahead(struct readahead_control *ractl, > max_pages); > rcu_read_unlock(); > > + start = round_down(start, min_nrpages); > + > + VM_BUG_ON(folio->index & (folio_nr_pages(folio) - 1)); > + > if (!start || start - index > max_pages) > return; > > ra->start = start; > ra->size = start - index; /* old async_size */ > + > ra->size += req_size; > - ra->size = get_next_ra_size(ra, max_pages); > + ra->size = get_next_ra_size(ra, min_nrpages, max_pages); > ra->async_size = ra->size; > goto readit; > } > @@ -646,7 +677,7 @@ static void ondemand_readahead(struct readahead_control *ractl, > > initial_readahead: > ra->start = index; > - ra->size = get_init_ra_size(req_size, max_pages); > + ra->size = get_init_ra_size(req_size, min_nrpages, max_pages); > ra->async_size = ra->size > req_size ? ra->size - req_size : ra->size; > > readit: > @@ -657,7 +688,7 @@ static void ondemand_readahead(struct readahead_control *ractl, > * Take care of maximum IO pages as above. > */ > if (index == ra->start && ra->size == ra->async_size) { > - add_pages = get_next_ra_size(ra, max_pages); > + add_pages = get_next_ra_size(ra, min_nrpages, max_pages); > if (ra->size + add_pages <= max_pages) { > ra->async_size = add_pages; > ra->size += add_pages; > @@ -668,6 +699,7 @@ static void ondemand_readahead(struct readahead_control *ractl, > } > > ractl->_index = ra->start; > + VM_BUG_ON(!IS_ALIGNED(ractl->_index, min_nrpages)); > page_cache_ra_order(ractl, ra, order); > } > > -- > 2.43.0 > >
On Tue, Feb 13, 2024 at 10:37:04AM +0100, Pankaj Raghav (Samsung) wrote: > From: Luis Chamberlain <mcgrof@kernel.org> > > Align the ra->start and ra->size to mapping_min_order in > ondemand_readahead(), and align the index to mapping_min_order in > force_page_cache_ra(). This will ensure that the folios allocated for > readahead that are added to the page cache are aligned to > mapping_min_order. > > Signed-off-by: Luis Chamberlain <mcgrof@kernel.org> > Signed-off-by: Pankaj Raghav <p.raghav@samsung.com> > --- > mm/readahead.c | 48 ++++++++++++++++++++++++++++++++++++++++-------- > 1 file changed, 40 insertions(+), 8 deletions(-) > > diff --git a/mm/readahead.c b/mm/readahead.c > index 4fa7d0e65706..5e1ec7705c78 100644 > --- a/mm/readahead.c > +++ b/mm/readahead.c > @@ -315,6 +315,7 @@ void force_page_cache_ra(struct readahead_control *ractl, > struct file_ra_state *ra = ractl->ra; > struct backing_dev_info *bdi = inode_to_bdi(mapping->host); > unsigned long max_pages, index; > + unsigned int min_nrpages = mapping_min_folio_nrpages(mapping); > > if (unlikely(!mapping->a_ops->read_folio && !mapping->a_ops->readahead)) > return; > @@ -324,6 +325,13 @@ void force_page_cache_ra(struct readahead_control *ractl, > * be up to the optimal hardware IO size > */ > index = readahead_index(ractl); > + if (!IS_ALIGNED(index, min_nrpages)) { > + unsigned long old_index = index; > + > + index = round_down(index, min_nrpages); > + nr_to_read += (old_index - index); > + } new_index = mapping_align_start_index(mapping, index); if (new_index != index) { nr_to_read += index - new_index; index = new_index } > + > max_pages = max_t(unsigned long, bdi->io_pages, ra->ra_pages); > nr_to_read = min_t(unsigned long, nr_to_read, max_pages); This needs to have a size of at least the minimum folio order size so readahead can fill entire folios, not get neutered to the maximum IO size the underlying storage supports. > while (nr_to_read) { > @@ -332,6 +340,7 @@ void force_page_cache_ra(struct readahead_control *ractl, > if (this_chunk > nr_to_read) > this_chunk = nr_to_read; > ractl->_index = index; > + VM_BUG_ON(!IS_ALIGNED(index, min_nrpages)); > do_page_cache_ra(ractl, this_chunk, 0); > > index += this_chunk; > @@ -344,11 +353,20 @@ void force_page_cache_ra(struct readahead_control *ractl, > * for small size, x 4 for medium, and x 2 for large > * for 128k (32 page) max ra > * 1-2 page = 16k, 3-4 page 32k, 5-8 page = 64k, > 8 page = 128k initial > + * > + * For higher order address space requirements we ensure no initial reads > + * are ever less than the min number of pages required. > + * > + * We *always* cap the max io size allowed by the device. > */ > -static unsigned long get_init_ra_size(unsigned long size, unsigned long max) > +static unsigned long get_init_ra_size(unsigned long size, > + unsigned int min_nrpages, > + unsigned long max) > { > unsigned long newsize = roundup_pow_of_two(size); > > + newsize = max_t(unsigned long, newsize, min_nrpages); This really doesn't need to care about min_nrpages. That rounding can be done in the caller when the new size is returned. > if (newsize <= max / 32) > newsize = newsize * 4; > else if (newsize <= max / 4) > @@ -356,6 +374,8 @@ static unsigned long get_init_ra_size(unsigned long size, unsigned long max) > else > newsize = max; > > + VM_BUG_ON(newsize & (min_nrpages - 1)); > + > return newsize; > } > > @@ -364,14 +384,16 @@ static unsigned long get_init_ra_size(unsigned long size, unsigned long max) > * return it as the new window size. > */ > static unsigned long get_next_ra_size(struct file_ra_state *ra, > + unsigned int min_nrpages, > unsigned long max) > { > - unsigned long cur = ra->size; > + unsigned long cur = max(ra->size, min_nrpages); > > if (cur < max / 16) > return 4 * cur; > if (cur <= max / 2) > return 2 * cur; > + > return max; Ditto. > } > > @@ -561,7 +583,11 @@ static void ondemand_readahead(struct readahead_control *ractl, > unsigned long add_pages; > pgoff_t index = readahead_index(ractl); > pgoff_t expected, prev_index; > - unsigned int order = folio ? folio_order(folio) : 0; > + unsigned int min_order = mapping_min_folio_order(ractl->mapping); > + unsigned int min_nrpages = mapping_min_folio_nrpages(ractl->mapping); > + unsigned int order = folio ? folio_order(folio) : min_order; Huh? If we have a folio, then the order is whatever that folio is, otherwise we use min_order. What if the folio is larger than min_order? Doesn't that mean that this: > @@ -583,8 +609,8 @@ static void ondemand_readahead(struct readahead_control *ractl, > expected = round_down(ra->start + ra->size - ra->async_size, > 1UL << order); > if (index == expected || index == (ra->start + ra->size)) { > - ra->start += ra->size; > - ra->size = get_next_ra_size(ra, max_pages); > + ra->start += round_down(ra->size, min_nrpages); > + ra->size = get_next_ra_size(ra, min_nrpages, max_pages); may set up the incorrect readahead range because the folio order is larger than min_nrpages? > ra->async_size = ra->size; > goto readit; > } > @@ -603,13 +629,18 @@ static void ondemand_readahead(struct readahead_control *ractl, > max_pages); > rcu_read_unlock(); > > + start = round_down(start, min_nrpages); start = mapping_align_start_index(mapping, start); > + > + VM_BUG_ON(folio->index & (folio_nr_pages(folio) - 1)); > + > if (!start || start - index > max_pages) > return; > > ra->start = start; > ra->size = start - index; /* old async_size */ > + > ra->size += req_size; > - ra->size = get_next_ra_size(ra, max_pages); > + ra->size = get_next_ra_size(ra, min_nrpages, max_pages); ra->size = max(min_nrpages, get_next_ra_size(ra, max_pages)); > ra->async_size = ra->size; > goto readit; > } > @@ -646,7 +677,7 @@ static void ondemand_readahead(struct readahead_control *ractl, > > initial_readahead: > ra->start = index; > - ra->size = get_init_ra_size(req_size, max_pages); > + ra->size = get_init_ra_size(req_size, min_nrpages, max_pages); ra->size = max(min_nrpages, get_init_ra_size(req_size, max_pages)); -Dave.
> > @@ -324,6 +325,13 @@ void force_page_cache_ra(struct readahead_control *ractl, > > * be up to the optimal hardware IO size > > */ > > index = readahead_index(ractl); > > + if (!IS_ALIGNED(index, min_nrpages)) { > > + unsigned long old_index = index; > > + > > + index = round_down(index, min_nrpages); > > + nr_to_read += (old_index - index); > > + } > > new_index = mapping_align_start_index(mapping, index); > if (new_index != index) { > nr_to_read += index - new_index; > index = new_index Looks good. > } > > > + > > max_pages = max_t(unsigned long, bdi->io_pages, ra->ra_pages); > > nr_to_read = min_t(unsigned long, nr_to_read, max_pages); > > This needs to have a size of at least the minimum folio order size > so readahead can fill entire folios, not get neutered to the maximum > IO size the underlying storage supports. So something like: > > max_pages = max_t(unsigned long, bdi->io_pages, ra->ra_pages); > > nr_to_read = min_t(unsigned long, nr_to_read, max_pages); nr_to_read = max(nr_to_read, min_order); > > > + * For higher order address space requirements we ensure no initial reads > > + * are ever less than the min number of pages required. > > + * > > + * We *always* cap the max io size allowed by the device. > > */ > > -static unsigned long get_init_ra_size(unsigned long size, unsigned long max) > > +static unsigned long get_init_ra_size(unsigned long size, > > + unsigned int min_nrpages, > > + unsigned long max) > > { > > unsigned long newsize = roundup_pow_of_two(size); > > > > + newsize = max_t(unsigned long, newsize, min_nrpages); > > This really doesn't need to care about min_nrpages. That rounding > can be done in the caller when the new size is returned. Sounds good. > > > if (newsize <= max / 32) > > newsize = newsize * 4; > > > > > > > @@ -561,7 +583,11 @@ static void ondemand_readahead(struct readahead_control *ractl, > > unsigned long add_pages; > > pgoff_t index = readahead_index(ractl); > > pgoff_t expected, prev_index; > > - unsigned int order = folio ? folio_order(folio) : 0; > > + unsigned int min_order = mapping_min_folio_order(ractl->mapping); > > + unsigned int min_nrpages = mapping_min_folio_nrpages(ractl->mapping); > > + unsigned int order = folio ? folio_order(folio) : min_order; > > Huh? If we have a folio, then the order is whatever that folio is, > otherwise we use min_order. What if the folio is larger than > min_order? Doesn't that mean that this: > > > @@ -583,8 +609,8 @@ static void ondemand_readahead(struct readahead_control *ractl, > > expected = round_down(ra->start + ra->size - ra->async_size, > > 1UL << order); > > if (index == expected || index == (ra->start + ra->size)) { > > - ra->start += ra->size; > > - ra->size = get_next_ra_size(ra, max_pages); > > + ra->start += round_down(ra->size, min_nrpages); > > + ra->size = get_next_ra_size(ra, min_nrpages, max_pages); > > may set up the incorrect readahead range because the folio order is > larger than min_nrpages? Hmm... So I think we should just increment ra->start by ra->size, and make sure to round the new size we get from get_next_ra_size() to min_nrpages. Then we will not disturb the readahead range and always increase the range in multiples of min_nrpages: ra->start += ra->size; ra->size = round_up(get_next_ra_size(ra, max_pages), min_nrpages); > > > ra->async_size = ra->size; > > goto readit; > > } > > @@ -603,13 +629,18 @@ static void ondemand_readahead(struct readahead_control *ractl, > > max_pages); > > rcu_read_unlock(); > > > > + start = round_down(start, min_nrpages); > > start = mapping_align_start_index(mapping, start); > > + > > + VM_BUG_ON(folio->index & (folio_nr_pages(folio) - 1)); > > + > > if (!start || start - index > max_pages) > > return; > > > > ra->start = start; > > ra->size = start - index; /* old async_size */ > > + > > ra->size += req_size; > > - ra->size = get_next_ra_size(ra, max_pages); > > + ra->size = get_next_ra_size(ra, min_nrpages, max_pages); > > ra->size = max(min_nrpages, get_next_ra_size(ra, max_pages)); If this is a round_up of size instead of max operation, we can always ensure the ra->start from index aligned to min_nrpages. See my reasoning in the previous comment. -- Pankaj
diff --git a/mm/readahead.c b/mm/readahead.c index 4fa7d0e65706..5e1ec7705c78 100644 --- a/mm/readahead.c +++ b/mm/readahead.c @@ -315,6 +315,7 @@ void force_page_cache_ra(struct readahead_control *ractl, struct file_ra_state *ra = ractl->ra; struct backing_dev_info *bdi = inode_to_bdi(mapping->host); unsigned long max_pages, index; + unsigned int min_nrpages = mapping_min_folio_nrpages(mapping); if (unlikely(!mapping->a_ops->read_folio && !mapping->a_ops->readahead)) return; @@ -324,6 +325,13 @@ void force_page_cache_ra(struct readahead_control *ractl, * be up to the optimal hardware IO size */ index = readahead_index(ractl); + if (!IS_ALIGNED(index, min_nrpages)) { + unsigned long old_index = index; + + index = round_down(index, min_nrpages); + nr_to_read += (old_index - index); + } + max_pages = max_t(unsigned long, bdi->io_pages, ra->ra_pages); nr_to_read = min_t(unsigned long, nr_to_read, max_pages); while (nr_to_read) { @@ -332,6 +340,7 @@ void force_page_cache_ra(struct readahead_control *ractl, if (this_chunk > nr_to_read) this_chunk = nr_to_read; ractl->_index = index; + VM_BUG_ON(!IS_ALIGNED(index, min_nrpages)); do_page_cache_ra(ractl, this_chunk, 0); index += this_chunk; @@ -344,11 +353,20 @@ void force_page_cache_ra(struct readahead_control *ractl, * for small size, x 4 for medium, and x 2 for large * for 128k (32 page) max ra * 1-2 page = 16k, 3-4 page 32k, 5-8 page = 64k, > 8 page = 128k initial + * + * For higher order address space requirements we ensure no initial reads + * are ever less than the min number of pages required. + * + * We *always* cap the max io size allowed by the device. */ -static unsigned long get_init_ra_size(unsigned long size, unsigned long max) +static unsigned long get_init_ra_size(unsigned long size, + unsigned int min_nrpages, + unsigned long max) { unsigned long newsize = roundup_pow_of_two(size); + newsize = max_t(unsigned long, newsize, min_nrpages); + if (newsize <= max / 32) newsize = newsize * 4; else if (newsize <= max / 4) @@ -356,6 +374,8 @@ static unsigned long get_init_ra_size(unsigned long size, unsigned long max) else newsize = max; + VM_BUG_ON(newsize & (min_nrpages - 1)); + return newsize; } @@ -364,14 +384,16 @@ static unsigned long get_init_ra_size(unsigned long size, unsigned long max) * return it as the new window size. */ static unsigned long get_next_ra_size(struct file_ra_state *ra, + unsigned int min_nrpages, unsigned long max) { - unsigned long cur = ra->size; + unsigned long cur = max(ra->size, min_nrpages); if (cur < max / 16) return 4 * cur; if (cur <= max / 2) return 2 * cur; + return max; } @@ -561,7 +583,11 @@ static void ondemand_readahead(struct readahead_control *ractl, unsigned long add_pages; pgoff_t index = readahead_index(ractl); pgoff_t expected, prev_index; - unsigned int order = folio ? folio_order(folio) : 0; + unsigned int min_order = mapping_min_folio_order(ractl->mapping); + unsigned int min_nrpages = mapping_min_folio_nrpages(ractl->mapping); + unsigned int order = folio ? folio_order(folio) : min_order; + + VM_BUG_ON(!IS_ALIGNED(ractl->_index, min_nrpages)); /* * If the request exceeds the readahead window, allow the read to @@ -583,8 +609,8 @@ static void ondemand_readahead(struct readahead_control *ractl, expected = round_down(ra->start + ra->size - ra->async_size, 1UL << order); if (index == expected || index == (ra->start + ra->size)) { - ra->start += ra->size; - ra->size = get_next_ra_size(ra, max_pages); + ra->start += round_down(ra->size, min_nrpages); + ra->size = get_next_ra_size(ra, min_nrpages, max_pages); ra->async_size = ra->size; goto readit; } @@ -603,13 +629,18 @@ static void ondemand_readahead(struct readahead_control *ractl, max_pages); rcu_read_unlock(); + start = round_down(start, min_nrpages); + + VM_BUG_ON(folio->index & (folio_nr_pages(folio) - 1)); + if (!start || start - index > max_pages) return; ra->start = start; ra->size = start - index; /* old async_size */ + ra->size += req_size; - ra->size = get_next_ra_size(ra, max_pages); + ra->size = get_next_ra_size(ra, min_nrpages, max_pages); ra->async_size = ra->size; goto readit; } @@ -646,7 +677,7 @@ static void ondemand_readahead(struct readahead_control *ractl, initial_readahead: ra->start = index; - ra->size = get_init_ra_size(req_size, max_pages); + ra->size = get_init_ra_size(req_size, min_nrpages, max_pages); ra->async_size = ra->size > req_size ? ra->size - req_size : ra->size; readit: @@ -657,7 +688,7 @@ static void ondemand_readahead(struct readahead_control *ractl, * Take care of maximum IO pages as above. */ if (index == ra->start && ra->size == ra->async_size) { - add_pages = get_next_ra_size(ra, max_pages); + add_pages = get_next_ra_size(ra, min_nrpages, max_pages); if (ra->size + add_pages <= max_pages) { ra->async_size = add_pages; ra->size += add_pages; @@ -668,6 +699,7 @@ static void ondemand_readahead(struct readahead_control *ractl, } ractl->_index = ra->start; + VM_BUG_ON(!IS_ALIGNED(ractl->_index, min_nrpages)); page_cache_ra_order(ractl, ra, order); }