From: Luis Chamberlain <mcgrof@xxxxxxxxxx>
Supporting mapping_min_order implies that we guarantee each folio in the
page cache has at least an order of mapping_min_order. So when adding new
folios to the page cache we must ensure the index used is aligned to the
mapping_min_order as the page cache requires the index to be aligned to
the order of the folio.
A higher order folio than min_order by definition is a multiple of the
min_order. If an index is aligned to an order higher than a min_order, it
will also be aligned to the min order.
This effectively introduces no new functional changes when min order is
not set other than a few rounding computations that should result in the
same value.
Signed-off-by: Luis Chamberlain <mcgrof@xxxxxxxxxx>
Signed-off-by: Pankaj Raghav <p.raghav@xxxxxxxxxxx>
---
include/linux/pagemap.h | 8 ++++++++
mm/filemap.c | 22 +++++++++++++---------
2 files changed, 21 insertions(+), 9 deletions(-)
diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index fc8eb9c94e9c..fe8e1fbb667d 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -1328,6 +1328,14 @@ struct readahead_control {
._index = i, \
}
+#define DEFINE_READAHEAD_ALIGNED(ractl, f, r, m, i) \
+ struct readahead_control ractl = { \
+ .file = f, \
+ .mapping = m, \
+ .ra = r, \
+ ._index = mapping_align_start_index(m, i), \
+ }
+
#define VM_READAHEAD_PAGES (SZ_128K / PAGE_SIZE)
void page_cache_ra_unbounded(struct readahead_control *,
diff --git a/mm/filemap.c b/mm/filemap.c
index 2b00442b9d19..bdf4f65f597c 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -2478,11 +2478,11 @@ static int filemap_get_pages(struct kiocb *iocb, size_t count,
struct file *filp = iocb->ki_filp;
struct address_space *mapping = filp->f_mapping;
struct file_ra_state *ra = &filp->f_ra;
- pgoff_t index = iocb->ki_pos >> PAGE_SHIFT;
- pgoff_t last_index;
+ pgoff_t index, last_index;
struct folio *folio;
int err = 0;
+ index = mapping_align_start_index(mapping, iocb->ki_pos >> PAGE_SHIFT);
/* "last_index" is the index of the page beyond the end of the read */
last_index = DIV_ROUND_UP(iocb->ki_pos + count, PAGE_SIZE);
retry:
@@ -2500,8 +2500,7 @@ static int filemap_get_pages(struct kiocb *iocb, size_t count,
if (!folio_batch_count(fbatch)) {
if (iocb->ki_flags & (IOCB_NOWAIT | IOCB_WAITQ))
return -EAGAIN;
- err = filemap_create_folio(filp, mapping,
- iocb->ki_pos >> PAGE_SHIFT, fbatch);
+ err = filemap_create_folio(filp, mapping, index, fbatch);
if (err == AOP_TRUNCATED_PAGE)
goto retry;
return err;
@@ -3093,7 +3092,7 @@ static struct file *do_sync_mmap_readahead(struct vm_fault *vmf)
struct file *file = vmf->vma->vm_file;
struct file_ra_state *ra = &file->f_ra;
struct address_space *mapping = file->f_mapping;
- DEFINE_READAHEAD(ractl, file, ra, mapping, vmf->pgoff);
+ DEFINE_READAHEAD_ALIGNED(ractl, file, ra, mapping, vmf->pgoff);
struct file *fpin = NULL;
unsigned long vm_flags = vmf->vma->vm_flags;
unsigned int mmap_miss;
@@ -3147,7 +3146,7 @@ static struct file *do_sync_mmap_readahead(struct vm_fault *vmf)
ra->start = max_t(long, 0, vmf->pgoff - ra->ra_pages / 2);
ra->size = ra->ra_pages;
ra->async_size = ra->ra_pages / 4;
- ractl._index = ra->start;
+ ractl._index = mapping_align_start_index(mapping, ra->start);
page_cache_ra_order(&ractl, ra, 0);
return fpin;
}
@@ -3162,7 +3161,7 @@ static struct file *do_async_mmap_readahead(struct vm_fault *vmf,
{
struct file *file = vmf->vma->vm_file;
struct file_ra_state *ra = &file->f_ra;
- DEFINE_READAHEAD(ractl, file, ra, file->f_mapping, vmf->pgoff);
+ DEFINE_READAHEAD_ALIGNED(ractl, file, ra, file->f_mapping, vmf->pgoff);
struct file *fpin = NULL;
unsigned int mmap_miss;
@@ -3211,11 +3210,12 @@ vm_fault_t filemap_fault(struct vm_fault *vmf)
struct file *fpin = NULL;
struct address_space *mapping = file->f_mapping;
struct inode *inode = mapping->host;
- pgoff_t max_idx, index = vmf->pgoff;
+ pgoff_t max_idx, index;
struct folio *folio;
vm_fault_t ret = 0;
bool mapping_locked = false;
+ index = mapping_align_start_index(mapping, vmf->pgoff);
max_idx = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE);
if (unlikely(index >= max_idx))
return VM_FAULT_SIGBUS;
@@ -3321,7 +3321,10 @@ vm_fault_t filemap_fault(struct vm_fault *vmf)
return VM_FAULT_SIGBUS;
}
- vmf->page = folio_file_page(folio, index);
+ VM_BUG_ON_FOLIO(folio_order(folio) < mapping_min_folio_order(mapping),
+ folio);
+
+ vmf->page = folio_file_page(folio, vmf->pgoff);
return ret | VM_FAULT_LOCKED;
page_not_uptodate:
@@ -3657,6 +3660,7 @@ static struct folio *do_read_cache_folio(struct address_space *mapping,
struct folio *folio;
int err;
+ index = mapping_align_start_index(mapping, index);
if (!filler)
filler = mapping->a_ops->read_folio;
repeat:
--
2.43.0
