| Message ID | 20210207170924.2933035-5-ruansy.fnst@cn.fujitsu.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | fsdax, xfs: Add reflink&dedupe support for fsdax | expand |
On Mon, Feb 08, 2021 at 01:09:21AM +0800, Shiyang Ruan 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@cn.fujitsu.com> > --- > fs/dax.c | 31 +++++++++++++++++++++++-------- > 1 file changed, 23 insertions(+), 8 deletions(-) > > diff --git a/fs/dax.c b/fs/dax.c > index b2195cbdf2dc..29698a3d2e37 100644 > --- a/fs/dax.c > +++ b/fs/dax.c > @@ -722,6 +722,9 @@ static int copy_cow_page_dax(struct block_device *bdev, struct dax_device *dax_d > return 0; > } > > +#define DAX_IF_DIRTY (1ULL << 0) > +#define DAX_IF_COW (1ULL << 1) The constants are ULL, but I see other flags only 'unsigned long' > + > /* > * 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 > @@ -731,14 +734,16 @@ static int copy_cow_page_dax(struct block_device *bdev, struct dax_device *dax_d > */ > 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) > + void *entry, pfn_t pfn, unsigned long flags, bool insert_flags) insert_flags is bool > { > void *new_entry = dax_make_entry(pfn, flags); > + bool dirty = insert_flags & DAX_IF_DIRTY; "insert_flags & DAX_IF_DIRTY" is "bool & ULL", this can't be right > + bool cow = insert_flags & DAX_IF_COW; Same > > 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)) > @@ -750,7 +755,7 @@ 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); > @@ -774,6 +779,9 @@ 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; > } > @@ -1319,6 +1327,7 @@ static vm_fault_t dax_iomap_pte_fault(struct vm_fault *vmf, pfn_t *pfnp, > void *entry; > pfn_t pfn; > void *kaddr; > + unsigned long insert_flags = 0; > > trace_dax_pte_fault(inode, vmf, ret); > /* > @@ -1444,8 +1453,10 @@ static vm_fault_t dax_iomap_pte_fault(struct vm_fault *vmf, pfn_t *pfnp, > > goto finish_iomap; > case IOMAP_UNWRITTEN: > - if (write && iomap.flags & IOMAP_F_SHARED) > + if (write && (iomap.flags & IOMAP_F_SHARED)) { > + insert_flags |= DAX_IF_COW; Here's an example of 'unsigned long = unsigned long long', though it'll work, it would be better to unify all the types. > goto cow; > + } > fallthrough; > case IOMAP_HOLE: > if (!write) { > @@ -1555,6 +1566,7 @@ static vm_fault_t dax_iomap_pmd_fault(struct vm_fault *vmf, pfn_t *pfnp, > int error; > pfn_t pfn; > void *kaddr; > + unsigned long insert_flags = 0; > > /* > * Check whether offset isn't beyond end of file now. Caller is > @@ -1670,14 +1682,17 @@ static vm_fault_t dax_iomap_pmd_fault(struct vm_fault *vmf, pfn_t *pfnp, > result = vmf_insert_pfn_pmd(vmf, pfn, write); > break; > case IOMAP_UNWRITTEN: > - if (write && iomap.flags & IOMAP_F_SHARED) > + if (write && (iomap.flags & IOMAP_F_SHARED)) { > + insert_flags |= DAX_IF_COW; > goto cow; > + } > fallthrough; > case IOMAP_HOLE: > - if (WARN_ON_ONCE(write)) > + if (!write) { > + result = dax_pmd_load_hole(&xas, vmf, &iomap, &entry); > break; > - result = dax_pmd_load_hole(&xas, vmf, &iomap, &entry); > - break; > + } > + fallthrough; > default: > WARN_ON_ONCE(1); > break; > -- > 2.30.0 > >
On 2021/2/16 下午9:11, David Sterba wrote: > On Mon, Feb 08, 2021 at 01:09:21AM +0800, Shiyang Ruan 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@cn.fujitsu.com> >> --- >> fs/dax.c | 31 +++++++++++++++++++++++-------- >> 1 file changed, 23 insertions(+), 8 deletions(-) >> >> diff --git a/fs/dax.c b/fs/dax.c >> index b2195cbdf2dc..29698a3d2e37 100644 >> --- a/fs/dax.c >> +++ b/fs/dax.c >> @@ -722,6 +722,9 @@ static int copy_cow_page_dax(struct block_device *bdev, struct dax_device *dax_d >> return 0; >> } >> >> +#define DAX_IF_DIRTY (1ULL << 0) >> +#define DAX_IF_COW (1ULL << 1) > > The constants are ULL, but I see other flags only 'unsigned long' > >> + >> /* >> * 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 >> @@ -731,14 +734,16 @@ static int copy_cow_page_dax(struct block_device *bdev, struct dax_device *dax_d >> */ >> 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) >> + void *entry, pfn_t pfn, unsigned long flags, bool insert_flags) > > insert_flags is bool > >> { >> void *new_entry = dax_make_entry(pfn, flags); >> + bool dirty = insert_flags & DAX_IF_DIRTY; > > "insert_flags & DAX_IF_DIRTY" is "bool & ULL", this can't be right This is a mistake caused by rebasing my old version patchset. Thanks for pointing out. I'll fix this in next version. > >> + bool cow = insert_flags & DAX_IF_COW; > > Same > >> >> 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)) >> @@ -750,7 +755,7 @@ 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); >> @@ -774,6 +779,9 @@ 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; >> } >> @@ -1319,6 +1327,7 @@ static vm_fault_t dax_iomap_pte_fault(struct vm_fault *vmf, pfn_t *pfnp, >> void *entry; >> pfn_t pfn; >> void *kaddr; >> + unsigned long insert_flags = 0; >> >> trace_dax_pte_fault(inode, vmf, ret); >> /* >> @@ -1444,8 +1453,10 @@ static vm_fault_t dax_iomap_pte_fault(struct vm_fault *vmf, pfn_t *pfnp, >> >> goto finish_iomap; >> case IOMAP_UNWRITTEN: >> - if (write && iomap.flags & IOMAP_F_SHARED) >> + if (write && (iomap.flags & IOMAP_F_SHARED)) { >> + insert_flags |= DAX_IF_COW; > > Here's an example of 'unsigned long = unsigned long long', though it'll > work, it would be better to unify all the types. Yes, I'll fix it. -- Thanks, Ruan Shiyang. > >> goto cow; >> + } >> fallthrough; >> case IOMAP_HOLE: >> if (!write) { >> @@ -1555,6 +1566,7 @@ static vm_fault_t dax_iomap_pmd_fault(struct vm_fault *vmf, pfn_t *pfnp, >> int error; >> pfn_t pfn; >> void *kaddr; >> + unsigned long insert_flags = 0; >> >> /* >> * Check whether offset isn't beyond end of file now. Caller is >> @@ -1670,14 +1682,17 @@ static vm_fault_t dax_iomap_pmd_fault(struct vm_fault *vmf, pfn_t *pfnp, >> result = vmf_insert_pfn_pmd(vmf, pfn, write); >> break; >> case IOMAP_UNWRITTEN: >> - if (write && iomap.flags & IOMAP_F_SHARED) >> + if (write && (iomap.flags & IOMAP_F_SHARED)) { >> + insert_flags |= DAX_IF_COW; >> goto cow; >> + } >> fallthrough; >> case IOMAP_HOLE: >> - if (WARN_ON_ONCE(write)) >> + if (!write) { >> + result = dax_pmd_load_hole(&xas, vmf, &iomap, &entry); >> break; >> - result = dax_pmd_load_hole(&xas, vmf, &iomap, &entry); >> - break; >> + } >> + fallthrough; >> default: >> WARN_ON_ONCE(1); >> break; >> -- >> 2.30.0 >> >> > >
diff --git a/fs/dax.c b/fs/dax.c index b2195cbdf2dc..29698a3d2e37 100644 --- a/fs/dax.c +++ b/fs/dax.c @@ -722,6 +722,9 @@ static int copy_cow_page_dax(struct block_device *bdev, struct dax_device *dax_d return 0; } +#define DAX_IF_DIRTY (1ULL << 0) +#define DAX_IF_COW (1ULL << 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 @@ -731,14 +734,16 @@ static int copy_cow_page_dax(struct block_device *bdev, struct dax_device *dax_d */ 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) + void *entry, pfn_t pfn, unsigned long flags, bool insert_flags) { 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)) @@ -750,7 +755,7 @@ 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); @@ -774,6 +779,9 @@ 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; } @@ -1319,6 +1327,7 @@ static vm_fault_t dax_iomap_pte_fault(struct vm_fault *vmf, pfn_t *pfnp, void *entry; pfn_t pfn; void *kaddr; + unsigned long insert_flags = 0; trace_dax_pte_fault(inode, vmf, ret); /* @@ -1444,8 +1453,10 @@ static vm_fault_t dax_iomap_pte_fault(struct vm_fault *vmf, pfn_t *pfnp, goto finish_iomap; case IOMAP_UNWRITTEN: - if (write && iomap.flags & IOMAP_F_SHARED) + if (write && (iomap.flags & IOMAP_F_SHARED)) { + insert_flags |= DAX_IF_COW; goto cow; + } fallthrough; case IOMAP_HOLE: if (!write) { @@ -1555,6 +1566,7 @@ static vm_fault_t dax_iomap_pmd_fault(struct vm_fault *vmf, pfn_t *pfnp, int error; pfn_t pfn; void *kaddr; + unsigned long insert_flags = 0; /* * Check whether offset isn't beyond end of file now. Caller is @@ -1670,14 +1682,17 @@ static vm_fault_t dax_iomap_pmd_fault(struct vm_fault *vmf, pfn_t *pfnp, result = vmf_insert_pfn_pmd(vmf, pfn, write); break; case IOMAP_UNWRITTEN: - if (write && iomap.flags & IOMAP_F_SHARED) + if (write && (iomap.flags & IOMAP_F_SHARED)) { + insert_flags |= DAX_IF_COW; goto cow; + } fallthrough; case IOMAP_HOLE: - if (WARN_ON_ONCE(write)) + if (!write) { + result = dax_pmd_load_hole(&xas, vmf, &iomap, &entry); break; - result = dax_pmd_load_hole(&xas, vmf, &iomap, &entry); - break; + } + fallthrough; default: WARN_ON_ONCE(1); break;