| Message ID | 20210816060359.1442450-4-ruansy.fnst@fujitsu.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | fsdax,xfs: Add reflink&dedupe support for fsdax | expand |
On Sun, Aug 15, 2021 at 11:05 PM Shiyang Ruan <ruansy.fnst@fujitsu.com> wrote: > > We replace the existing entry to the newly allocated one in case of CoW. > Also, we mark the entry as PAGECACHE_TAG_TOWRITE so writeback marks this > entry as writeprotected. This helps us snapshots so new write > pagefaults after snapshots trigger a CoW. > > Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com> > Signed-off-by: Shiyang Ruan <ruansy.fnst@fujitsu.com> > Reviewed-by: Christoph Hellwig <hch@lst.de> > Reviewed-by: Ritesh Harjani <riteshh@linux.ibm.com> > Reviewed-by: Darrick J. Wong <djwong@kernel.org> > --- > fs/dax.c | 39 ++++++++++++++++++++++++++++----------- > 1 file changed, 28 insertions(+), 11 deletions(-) > > diff --git a/fs/dax.c b/fs/dax.c > index 697a7b7bb96f..e49ba68cc7e4 100644 > --- a/fs/dax.c > +++ b/fs/dax.c > @@ -734,6 +734,10 @@ static int copy_cow_page_dax(struct block_device *bdev, struct dax_device *dax_d > return 0; > } > > +/* DAX Insert Flag: The state of the entry we insert */ > +#define DAX_IF_DIRTY (1 << 0) > +#define DAX_IF_COW (1 << 1) > + > /* > * By this point grab_mapping_entry() has ensured that we have a locked entry > * of the appropriate size so we don't have to worry about downgrading PMDs to > @@ -741,16 +745,19 @@ static int copy_cow_page_dax(struct block_device *bdev, struct dax_device *dax_d > * already in the tree, we will skip the insertion and just dirty the PMD as > * appropriate. > */ > -static void *dax_insert_entry(struct xa_state *xas, > - struct address_space *mapping, struct vm_fault *vmf, > - void *entry, pfn_t pfn, unsigned long flags, bool dirty) > +static void *dax_insert_entry(struct xa_state *xas, struct vm_fault *vmf, > + void *entry, pfn_t pfn, unsigned long flags, > + unsigned int insert_flags) I'm late, so feel free to ignore this style feedback, but what about changing the signature to: static void *dax_insert_entry(struct xa_state *xas, struct vm_fault *vmf, const struct iomap_iter *iter, void *entry, pfn_t pfn, unsigned long flags) > { > + struct address_space *mapping = vmf->vma->vm_file->f_mapping; > void *new_entry = dax_make_entry(pfn, flags); > + bool dirty = insert_flags & DAX_IF_DIRTY; > + bool cow = insert_flags & DAX_IF_COW; ...and then calculate these flags from the source data. I'm just reacting to "yet more flags". So, take it or leave it, Reviewed-by: Dan Williams <dan.j.williams@intel.com>
On Thu, Aug 19, 2021 at 03:54:01PM -0700, Dan Williams wrote: > > static void *dax_insert_entry(struct xa_state *xas, struct vm_fault *vmf, > const struct iomap_iter *iter, void > *entry, pfn_t pfn, > unsigned long flags) > > > > { > > + struct address_space *mapping = vmf->vma->vm_file->f_mapping; > > void *new_entry = dax_make_entry(pfn, flags); > > + bool dirty = insert_flags & DAX_IF_DIRTY; > > + bool cow = insert_flags & DAX_IF_COW; > > ...and then calculate these flags from the source data. I'm just > reacting to "yet more flags". Except for the overly long line above that seems like a good idea. The iomap_iter didn't exist for most of the time this patch has been around.
On 2021/8/23 20:57, Christoph Hellwig wrote: > On Thu, Aug 19, 2021 at 03:54:01PM -0700, Dan Williams wrote: >> >> static void *dax_insert_entry(struct xa_state *xas, struct vm_fault *vmf, >> const struct iomap_iter *iter, void >> *entry, pfn_t pfn, >> unsigned long flags) >> >> >>> { >>> + struct address_space *mapping = vmf->vma->vm_file->f_mapping; >>> void *new_entry = dax_make_entry(pfn, flags); >>> + bool dirty = insert_flags & DAX_IF_DIRTY; >>> + bool cow = insert_flags & DAX_IF_COW; >> >> ...and then calculate these flags from the source data. I'm just >> reacting to "yet more flags". > > Except for the overly long line above that seems like a good idea. > The iomap_iter didn't exist for most of the time this patch has been > around. > So should I reuse the iter->flags to pass the insert_flags? (left shift it to higher bits) -- Thanks, Ruan.
On Thu, Aug 26, 2021 at 8:22 PM Shiyang Ruan <ruansy.fnst@fujitsu.com> wrote: > > > > On 2021/8/23 20:57, Christoph Hellwig wrote: > > On Thu, Aug 19, 2021 at 03:54:01PM -0700, Dan Williams wrote: > >> > >> static void *dax_insert_entry(struct xa_state *xas, struct vm_fault *vmf, > >> const struct iomap_iter *iter, void > >> *entry, pfn_t pfn, > >> unsigned long flags) > >> > >> > >>> { > >>> + struct address_space *mapping = vmf->vma->vm_file->f_mapping; > >>> void *new_entry = dax_make_entry(pfn, flags); > >>> + bool dirty = insert_flags & DAX_IF_DIRTY; > >>> + bool cow = insert_flags & DAX_IF_COW; > >> > >> ...and then calculate these flags from the source data. I'm just > >> reacting to "yet more flags". > > > > Except for the overly long line above that seems like a good idea. > > The iomap_iter didn't exist for most of the time this patch has been > > around. > > > > So should I reuse the iter->flags to pass the insert_flags? (left shift > it to higher bits) No, the advice is to just pass the @iter to dax_insert_entry directly and calculate @dirty and @cow internally.
On 2021/8/27 13:00, Dan Williams wrote: > On Thu, Aug 26, 2021 at 8:22 PM Shiyang Ruan <ruansy.fnst@fujitsu.com> wrote: >> >> >> >> On 2021/8/23 20:57, Christoph Hellwig wrote: >>> On Thu, Aug 19, 2021 at 03:54:01PM -0700, Dan Williams wrote: >>>> >>>> static void *dax_insert_entry(struct xa_state *xas, struct vm_fault *vmf, >>>> const struct iomap_iter *iter, void >>>> *entry, pfn_t pfn, >>>> unsigned long flags) >>>> >>>> >>>>> { >>>>> + struct address_space *mapping = vmf->vma->vm_file->f_mapping; >>>>> void *new_entry = dax_make_entry(pfn, flags); >>>>> + bool dirty = insert_flags & DAX_IF_DIRTY; >>>>> + bool cow = insert_flags & DAX_IF_COW; >>>> >>>> ...and then calculate these flags from the source data. I'm just >>>> reacting to "yet more flags". >>> >>> Except for the overly long line above that seems like a good idea. >>> The iomap_iter didn't exist for most of the time this patch has been >>> around. >>> >> >> So should I reuse the iter->flags to pass the insert_flags? (left shift >> it to higher bits) > > No, the advice is to just pass the @iter to dax_insert_entry directly > and calculate @dirty and @cow internally. > I see. Yes, they can be calculated inside the dax_insert_entry() because it already has enough arguments. -- Thanks, Ruan.
diff --git a/fs/dax.c b/fs/dax.c index 697a7b7bb96f..e49ba68cc7e4 100644 --- a/fs/dax.c +++ b/fs/dax.c @@ -734,6 +734,10 @@ static int copy_cow_page_dax(struct block_device *bdev, struct dax_device *dax_d return 0; } +/* DAX Insert Flag: The state of the entry we insert */ +#define DAX_IF_DIRTY (1 << 0) +#define DAX_IF_COW (1 << 1) + /* * By this point grab_mapping_entry() has ensured that we have a locked entry * of the appropriate size so we don't have to worry about downgrading PMDs to @@ -741,16 +745,19 @@ static int copy_cow_page_dax(struct block_device *bdev, struct dax_device *dax_d * already in the tree, we will skip the insertion and just dirty the PMD as * appropriate. */ -static void *dax_insert_entry(struct xa_state *xas, - struct address_space *mapping, struct vm_fault *vmf, - void *entry, pfn_t pfn, unsigned long flags, bool dirty) +static void *dax_insert_entry(struct xa_state *xas, struct vm_fault *vmf, + void *entry, pfn_t pfn, unsigned long flags, + unsigned int insert_flags) { + struct address_space *mapping = vmf->vma->vm_file->f_mapping; void *new_entry = dax_make_entry(pfn, flags); + bool dirty = insert_flags & DAX_IF_DIRTY; + bool cow = insert_flags & DAX_IF_COW; if (dirty) __mark_inode_dirty(mapping->host, I_DIRTY_PAGES); - if (dax_is_zero_entry(entry) && !(flags & DAX_ZERO_PAGE)) { + if (cow || (dax_is_zero_entry(entry) && !(flags & DAX_ZERO_PAGE))) { unsigned long index = xas->xa_index; /* we are replacing a zero page with block mapping */ if (dax_is_pmd_entry(entry)) @@ -762,7 +769,7 @@ static void *dax_insert_entry(struct xa_state *xas, xas_reset(xas); xas_lock_irq(xas); - if (dax_is_zero_entry(entry) || dax_is_empty_entry(entry)) { + if (cow || dax_is_zero_entry(entry) || dax_is_empty_entry(entry)) { void *old; dax_disassociate_entry(entry, mapping, false); @@ -786,6 +793,9 @@ static void *dax_insert_entry(struct xa_state *xas, if (dirty) xas_set_mark(xas, PAGECACHE_TAG_DIRTY); + if (cow) + xas_set_mark(xas, PAGECACHE_TAG_TOWRITE); + xas_unlock_irq(xas); return entry; } @@ -1121,8 +1131,7 @@ static vm_fault_t dax_load_hole(struct xa_state *xas, pfn_t pfn = pfn_to_pfn_t(my_zero_pfn(vaddr)); vm_fault_t ret; - *entry = dax_insert_entry(xas, mapping, vmf, *entry, pfn, - DAX_ZERO_PAGE, false); + *entry = dax_insert_entry(xas, vmf, *entry, pfn, DAX_ZERO_PAGE, 0); ret = vmf_insert_mixed(vmf->vma, vaddr, pfn); trace_dax_load_hole(inode, vmf, ret); @@ -1149,8 +1158,8 @@ static vm_fault_t dax_pmd_load_hole(struct xa_state *xas, struct vm_fault *vmf, goto fallback; pfn = page_to_pfn_t(zero_page); - *entry = dax_insert_entry(xas, mapping, vmf, *entry, pfn, - DAX_PMD | DAX_ZERO_PAGE, false); + *entry = dax_insert_entry(xas, vmf, *entry, pfn, + DAX_PMD | DAX_ZERO_PAGE, 0); if (arch_needs_pgtable_deposit()) { pgtable = pte_alloc_one(vma->vm_mm); @@ -1461,6 +1470,7 @@ static vm_fault_t dax_fault_iter(struct vm_fault *vmf, bool write = vmf->flags & FAULT_FLAG_WRITE; bool sync = dax_fault_is_synchronous(iter->flags, vmf->vma, iomap); unsigned long entry_flags = pmd ? DAX_PMD : 0; + unsigned int insert_flags = 0; int err = 0; pfn_t pfn; void *kaddr; @@ -1485,8 +1495,15 @@ static vm_fault_t dax_fault_iter(struct vm_fault *vmf, if (err) return pmd ? VM_FAULT_FALLBACK : dax_fault_return(err); - *entry = dax_insert_entry(xas, mapping, vmf, *entry, pfn, entry_flags, - write && !sync); + if (write) { + if (!sync) + insert_flags |= DAX_IF_DIRTY; + if (iomap->flags & IOMAP_F_SHARED) + insert_flags |= DAX_IF_COW; + } + + *entry = dax_insert_entry(xas, vmf, *entry, pfn, entry_flags, + insert_flags); if (write && srcmap->addr != IOMAP_HOLE && srcmap->addr != iomap->addr) {