| Message ID | 20210319015237.993880-3-ruansy.fnst@fujitsu.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | fsdax,xfs: Add reflink&dedupe support for fsdax | expand |
On 3/19/21 7:22 AM, Shiyang Ruan wrote: > The core logic in the two dax page fault functions is similar. So, move > the logic into a common helper function. Also, to facilitate the > addition of new features, such as CoW, switch-case is no longer used to > handle different iomap types. > > Signed-off-by: Shiyang Ruan <ruansy.fnst@fujitsu.com> > --- > fs/dax.c | 291 +++++++++++++++++++++++++++---------------------------- > 1 file changed, 145 insertions(+), 146 deletions(-) > > diff --git a/fs/dax.c b/fs/dax.c > index 7031e4302b13..33ddad0f3091 100644 > --- a/fs/dax.c > +++ b/fs/dax.c > @@ -1053,6 +1053,66 @@ static vm_fault_t dax_load_hole(struct xa_state *xas, > return ret; > } > > +#ifdef CONFIG_FS_DAX_PMD > +static vm_fault_t dax_pmd_load_hole(struct xa_state *xas, struct vm_fault *vmf, > + struct iomap *iomap, void **entry) > +{ > + struct address_space *mapping = vmf->vma->vm_file->f_mapping; > + unsigned long pmd_addr = vmf->address & PMD_MASK; > + struct vm_area_struct *vma = vmf->vma; > + struct inode *inode = mapping->host; > + pgtable_t pgtable = NULL; > + struct page *zero_page; > + spinlock_t *ptl; > + pmd_t pmd_entry; > + pfn_t pfn; > + > + zero_page = mm_get_huge_zero_page(vmf->vma->vm_mm); > + > + if (unlikely(!zero_page)) > + goto fallback; > + > + pfn = page_to_pfn_t(zero_page); > + *entry = dax_insert_entry(xas, mapping, vmf, *entry, pfn, > + DAX_PMD | DAX_ZERO_PAGE, false); > + > + if (arch_needs_pgtable_deposit()) { > + pgtable = pte_alloc_one(vma->vm_mm); > + if (!pgtable) > + return VM_FAULT_OOM; > + } > + > + ptl = pmd_lock(vmf->vma->vm_mm, vmf->pmd); > + if (!pmd_none(*(vmf->pmd))) { > + spin_unlock(ptl); > + goto fallback; > + } > + > + if (pgtable) { > + pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, pgtable); > + mm_inc_nr_ptes(vma->vm_mm); > + } > + pmd_entry = mk_pmd(zero_page, vmf->vma->vm_page_prot); > + pmd_entry = pmd_mkhuge(pmd_entry); > + set_pmd_at(vmf->vma->vm_mm, pmd_addr, vmf->pmd, pmd_entry); > + spin_unlock(ptl); > + trace_dax_pmd_load_hole(inode, vmf, zero_page, *entry); > + return VM_FAULT_NOPAGE; > + > +fallback: > + if (pgtable) > + pte_free(vma->vm_mm, pgtable); > + trace_dax_pmd_load_hole_fallback(inode, vmf, zero_page, *entry); > + return VM_FAULT_FALLBACK; > +} > +#else > +static vm_fault_t dax_pmd_load_hole(struct xa_state *xas, struct vm_fault *vmf, > + struct iomap *iomap, void **entry) > +{ > + return VM_FAULT_FALLBACK; > +} > +#endif /* CONFIG_FS_DAX_PMD */ > + > s64 dax_iomap_zero(loff_t pos, u64 length, struct iomap *iomap) > { > sector_t sector = iomap_sector(iomap, pos & PAGE_MASK); > @@ -1289,6 +1349,61 @@ static int dax_fault_cow_page(struct vm_fault *vmf, struct iomap *iomap, > return 0; > } > > +/** > + * dax_fault_actor - Common actor to handle pfn insertion in PTE/PMD fault. > + * @vmf: vm fault instance > + * @pfnp: pfn to be returned > + * @xas: the dax mapping tree of a file > + * @entry: an unlocked dax entry to be inserted > + * @pmd: distinguish whether it is a pmd fault > + * @flags: iomap flags > + * @iomap: from iomap_begin() > + * @srcmap: from iomap_begin(), not equal to iomap if it is a CoW > + */ > +static vm_fault_t dax_fault_actor(struct vm_fault *vmf, pfn_t *pfnp, > + struct xa_state *xas, void *entry, bool pmd, unsigned int flags, > + struct iomap *iomap, struct iomap *srcmap) > +{ > + struct address_space *mapping = vmf->vma->vm_file->f_mapping; > + size_t size = pmd ? PMD_SIZE : PAGE_SIZE; > + loff_t pos = (loff_t)xas->xa_offset << PAGE_SHIFT; shouldn't we use xa_index here for pos ? (loff_t)xas->xa_index << PAGE_SHIFT; > + bool write = vmf->flags & FAULT_FLAG_WRITE; > + bool sync = dax_fault_is_synchronous(flags, vmf->vma, iomap); > + int err = 0; > + pfn_t pfn; > + > + /* if we are reading UNWRITTEN and HOLE, return a hole. */ > + if (!write && > + (iomap->type == IOMAP_UNWRITTEN || iomap->type == IOMAP_HOLE)) { > + if (!pmd) > + return dax_load_hole(xas, mapping, &entry, vmf); > + else > + return dax_pmd_load_hole(xas, vmf, iomap, &entry); > + } > + > + if (iomap->type != IOMAP_MAPPED) { > + WARN_ON_ONCE(1); > + return VM_FAULT_SIGBUS; > + } So now in case if mapping is not mapped, we always cause VM_FAULT_SIGBUG. But earlier we were only doing WARN_ON_ONCE(1). Can you pls help answer why the change in behavior? > + > + err = dax_iomap_pfn(iomap, pos, size, &pfn); > + if (err) > + return dax_fault_return(err); Same case here as well. This could return SIGBUS while earlier I am not sure why were we only returning FALLBACK? > + > + entry = dax_insert_entry(xas, mapping, vmf, entry, pfn, 0, > + write && !sync); In dax_insert_entry() we are passing 0 as flags. We should be passing DAX_PMD/DAX_PTE no? > + > + if (sync) > + return dax_fault_synchronous_pfnp(pfnp, pfn); > + /* handle PMD case here */ > + if (pmd) > + return vmf_insert_pfn_pmd(vmf, pfn, write); /* handle PTE case here */ > + if (write) > + return vmf_insert_mixed_mkwrite(vmf->vma, vmf->address, pfn); > + else > + return vmf_insert_mixed(vmf->vma, vmf->address, pfn); > +} It is easy to miss the return from if(pmd) case while reading. A comment like above could be helpful for code review. > + > static vm_fault_t dax_iomap_pte_fault(struct vm_fault *vmf, pfn_t *pfnp, > int *iomap_errp, const struct iomap_ops *ops) > { > @@ -1296,17 +1411,14 @@ static vm_fault_t dax_iomap_pte_fault(struct vm_fault *vmf, pfn_t *pfnp, > struct address_space *mapping = vma->vm_file->f_mapping; > XA_STATE(xas, &mapping->i_pages, vmf->pgoff); > struct inode *inode = mapping->host; > - unsigned long vaddr = vmf->address; > loff_t pos = (loff_t)vmf->pgoff << PAGE_SHIFT; > struct iomap iomap = { .type = IOMAP_HOLE }; > struct iomap srcmap = { .type = IOMAP_HOLE }; > unsigned flags = IOMAP_FAULT; > int error, major = 0; > bool write = vmf->flags & FAULT_FLAG_WRITE; > - bool sync; > vm_fault_t ret = 0; > void *entry; > - pfn_t pfn; > > trace_dax_pte_fault(inode, vmf, ret); > /* > @@ -1352,8 +1464,8 @@ static vm_fault_t dax_iomap_pte_fault(struct vm_fault *vmf, pfn_t *pfnp, > goto unlock_entry; > } > if (WARN_ON_ONCE(iomap.offset + iomap.length < pos + PAGE_SIZE)) { > - error = -EIO; /* fs corruption? */ > - goto error_finish_iomap; > + ret = VM_FAULT_SIGBUS; /* fs corruption? */ > + goto finish_iomap; > } > > if (vmf->cow_page) { > @@ -1363,49 +1475,19 @@ static vm_fault_t dax_iomap_pte_fault(struct vm_fault *vmf, pfn_t *pfnp, > goto finish_iomap; > } > > - sync = dax_fault_is_synchronous(flags, vma, &iomap); > - > - switch (iomap.type) { > - case IOMAP_MAPPED: > - if (iomap.flags & IOMAP_F_NEW) { > - count_vm_event(PGMAJFAULT); > - count_memcg_event_mm(vma->vm_mm, PGMAJFAULT); > - major = VM_FAULT_MAJOR; > - } > - error = dax_iomap_pfn(&iomap, pos, PAGE_SIZE, &pfn); > - if (error < 0) > - goto error_finish_iomap; > - > - entry = dax_insert_entry(&xas, mapping, vmf, entry, pfn, > - 0, write && !sync); > - > - if (sync) { > - ret = dax_fault_synchronous_pfnp(pfnp, pfn); > - goto finish_iomap; > - } > - trace_dax_insert_mapping(inode, vmf, entry); > - if (write) > - ret = vmf_insert_mixed_mkwrite(vma, vaddr, pfn); > - else > - ret = vmf_insert_mixed(vma, vaddr, pfn); > - > + ret = dax_fault_actor(vmf, pfnp, &xas, entry, false, flags, > + &iomap, &srcmap); > + if (ret == VM_FAULT_SIGBUS) > goto finish_iomap; > - case IOMAP_UNWRITTEN: > - case IOMAP_HOLE: > - if (!write) { > - ret = dax_load_hole(&xas, mapping, &entry, vmf); > - goto finish_iomap; > - } > - fallthrough; > - default: > - WARN_ON_ONCE(1); > - error = -EIO; > - break; > + > + /* read/write MAPPED, CoW UNWRITTEN */ > + if (iomap.flags & IOMAP_F_NEW) { > + count_vm_event(PGMAJFAULT); > + count_memcg_event_mm(vma->vm_mm, PGMAJFAULT); > + major = VM_FAULT_MAJOR; > } It is much better if above accounting is also done in dax_fault_actor() function itself. Then at the end of this function we need to just do "return ret" instead of "return ret | major" > > - error_finish_iomap: > - ret = dax_fault_return(error); > - finish_iomap: > +finish_iomap: > if (ops->iomap_end) { > int copied = PAGE_SIZE; > > @@ -1419,66 +1501,14 @@ static vm_fault_t dax_iomap_pte_fault(struct vm_fault *vmf, pfn_t *pfnp, > */ > ops->iomap_end(inode, pos, PAGE_SIZE, copied, flags, &iomap); > } > - unlock_entry: > +unlock_entry: > dax_unlock_entry(&xas, entry); > - out: > +out: > trace_dax_pte_fault_done(inode, vmf, ret); > return ret | major; > } -ritesh
> -----Original Message----- > From: Ritesh Harjani <riteshh@linux.ibm.com> > Sent: Tuesday, March 23, 2021 11:48 PM > Subject: Re: [PATCH v3 02/10] fsdax: Factor helper: dax_fault_actor() > > > > On 3/19/21 7:22 AM, Shiyang Ruan wrote: > > The core logic in the two dax page fault functions is similar. So, > > move the logic into a common helper function. Also, to facilitate the > > addition of new features, such as CoW, switch-case is no longer used > > to handle different iomap types. > > > > Signed-off-by: Shiyang Ruan <ruansy.fnst@fujitsu.com> > > --- > > fs/dax.c | 291 +++++++++++++++++++++++++++---------------------------- > > 1 file changed, 145 insertions(+), 146 deletions(-) > > > > diff --git a/fs/dax.c b/fs/dax.c > > index 7031e4302b13..33ddad0f3091 100644 > > --- a/fs/dax.c > > +++ b/fs/dax.c > > @@ -1053,6 +1053,66 @@ static vm_fault_t dax_load_hole(struct xa_state > *xas, > > return ret; > > } > > > > +#ifdef CONFIG_FS_DAX_PMD > > +static vm_fault_t dax_pmd_load_hole(struct xa_state *xas, struct vm_fault > *vmf, > > + struct iomap *iomap, void **entry) > > +{ > > + struct address_space *mapping = vmf->vma->vm_file->f_mapping; > > + unsigned long pmd_addr = vmf->address & PMD_MASK; > > + struct vm_area_struct *vma = vmf->vma; > > + struct inode *inode = mapping->host; > > + pgtable_t pgtable = NULL; > > + struct page *zero_page; > > + spinlock_t *ptl; > > + pmd_t pmd_entry; > > + pfn_t pfn; > > + > > + zero_page = mm_get_huge_zero_page(vmf->vma->vm_mm); > > + > > + if (unlikely(!zero_page)) > > + goto fallback; > > + > > + pfn = page_to_pfn_t(zero_page); > > + *entry = dax_insert_entry(xas, mapping, vmf, *entry, pfn, > > + DAX_PMD | DAX_ZERO_PAGE, false); > > + > > + if (arch_needs_pgtable_deposit()) { > > + pgtable = pte_alloc_one(vma->vm_mm); > > + if (!pgtable) > > + return VM_FAULT_OOM; > > + } > > + > > + ptl = pmd_lock(vmf->vma->vm_mm, vmf->pmd); > > + if (!pmd_none(*(vmf->pmd))) { > > + spin_unlock(ptl); > > + goto fallback; > > + } > > + > > + if (pgtable) { > > + pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, pgtable); > > + mm_inc_nr_ptes(vma->vm_mm); > > + } > > + pmd_entry = mk_pmd(zero_page, vmf->vma->vm_page_prot); > > + pmd_entry = pmd_mkhuge(pmd_entry); > > + set_pmd_at(vmf->vma->vm_mm, pmd_addr, vmf->pmd, pmd_entry); > > + spin_unlock(ptl); > > + trace_dax_pmd_load_hole(inode, vmf, zero_page, *entry); > > + return VM_FAULT_NOPAGE; > > + > > +fallback: > > + if (pgtable) > > + pte_free(vma->vm_mm, pgtable); > > + trace_dax_pmd_load_hole_fallback(inode, vmf, zero_page, *entry); > > + return VM_FAULT_FALLBACK; > > +} > > +#else > > +static vm_fault_t dax_pmd_load_hole(struct xa_state *xas, struct vm_fault > *vmf, > > + struct iomap *iomap, void **entry) > > +{ > > + return VM_FAULT_FALLBACK; > > +} > > +#endif /* CONFIG_FS_DAX_PMD */ > > + > > s64 dax_iomap_zero(loff_t pos, u64 length, struct iomap *iomap) > > { > > sector_t sector = iomap_sector(iomap, pos & PAGE_MASK); @@ > -1289,6 > > +1349,61 @@ static int dax_fault_cow_page(struct vm_fault *vmf, struct > iomap *iomap, > > return 0; > > } > > > > +/** > > + * dax_fault_actor - Common actor to handle pfn insertion in PTE/PMD fault. > > + * @vmf: vm fault instance > > + * @pfnp: pfn to be returned > > + * @xas: the dax mapping tree of a file > > + * @entry: an unlocked dax entry to be inserted > > + * @pmd: distinguish whether it is a pmd fault > > + * @flags: iomap flags > > + * @iomap: from iomap_begin() > > + * @srcmap: from iomap_begin(), not equal to iomap if it is a CoW > > + */ > > +static vm_fault_t dax_fault_actor(struct vm_fault *vmf, pfn_t *pfnp, > > + struct xa_state *xas, void *entry, bool pmd, unsigned int flags, > > + struct iomap *iomap, struct iomap *srcmap) { > > + struct address_space *mapping = vmf->vma->vm_file->f_mapping; > > + size_t size = pmd ? PMD_SIZE : PAGE_SIZE; > > + loff_t pos = (loff_t)xas->xa_offset << PAGE_SHIFT; > > shouldn't we use xa_index here for pos ? > (loff_t)xas->xa_index << PAGE_SHIFT; Yes. > > > + bool write = vmf->flags & FAULT_FLAG_WRITE; > > + bool sync = dax_fault_is_synchronous(flags, vmf->vma, iomap); > > + int err = 0; > > + pfn_t pfn; > > + > > + /* if we are reading UNWRITTEN and HOLE, return a hole. */ > > + if (!write && > > + (iomap->type == IOMAP_UNWRITTEN || iomap->type == > IOMAP_HOLE)) { > > + if (!pmd) > > + return dax_load_hole(xas, mapping, &entry, vmf); > > + else > > + return dax_pmd_load_hole(xas, vmf, iomap, &entry); > > + } > > + > > + if (iomap->type != IOMAP_MAPPED) { > > + WARN_ON_ONCE(1); > > + return VM_FAULT_SIGBUS; > > + } > > So now in case if mapping is not mapped, we always cause VM_FAULT_SIGBUG. > But earlier we were only doing WARN_ON_ONCE(1). > Can you pls help answer why the change in behavior? > The behavior in PTE fault was always check the error code by dax_fault_return(error) after WARN_ON_ONCE(1). So, I moved the dax_fault_return() into dax_fault_actor(). But I just found that, in PMD fault, it didn't do this check. So, I think I should move dax_fault_return() outside the dax_fault_actor() to keep the previous logic. > > > > > + > > + err = dax_iomap_pfn(iomap, pos, size, &pfn); > > + if (err) > > + return dax_fault_return(err); > > Same case here as well. This could return SIGBUS while earlier I am not sure > why were we only returning FALLBACK? > Yes. Thanks for pointing out. > > > + > > + entry = dax_insert_entry(xas, mapping, vmf, entry, pfn, 0, > > + write && !sync); > > In dax_insert_entry() we are passing 0 as flags. > We should be passing DAX_PMD/DAX_PTE no? > My mistake. > > > + > > + if (sync) > > + return dax_fault_synchronous_pfnp(pfnp, pfn); > > + > > > /* handle PMD case here */ > > + if (pmd) > > + return vmf_insert_pfn_pmd(vmf, pfn, write); > > /* handle PTE case here */ > > + if (write) > > + return vmf_insert_mixed_mkwrite(vmf->vma, vmf->address, pfn); > > + else > > + return vmf_insert_mixed(vmf->vma, vmf->address, pfn); > > +} > > It is easy to miss the return from if(pmd) case while reading. > A comment like above could be helpful for code review. > > > > + > > static vm_fault_t dax_iomap_pte_fault(struct vm_fault *vmf, pfn_t *pfnp, > > int *iomap_errp, const struct iomap_ops *ops) > > { > > @@ -1296,17 +1411,14 @@ static vm_fault_t dax_iomap_pte_fault(struct > vm_fault *vmf, pfn_t *pfnp, > > struct address_space *mapping = vma->vm_file->f_mapping; > > XA_STATE(xas, &mapping->i_pages, vmf->pgoff); > > struct inode *inode = mapping->host; > > - unsigned long vaddr = vmf->address; > > loff_t pos = (loff_t)vmf->pgoff << PAGE_SHIFT; > > struct iomap iomap = { .type = IOMAP_HOLE }; > > struct iomap srcmap = { .type = IOMAP_HOLE }; > > unsigned flags = IOMAP_FAULT; > > int error, major = 0; > > bool write = vmf->flags & FAULT_FLAG_WRITE; > > - bool sync; > > vm_fault_t ret = 0; > > void *entry; > > - pfn_t pfn; > > > > trace_dax_pte_fault(inode, vmf, ret); > > /* > > @@ -1352,8 +1464,8 @@ static vm_fault_t dax_iomap_pte_fault(struct > vm_fault *vmf, pfn_t *pfnp, > > goto unlock_entry; > > } > > if (WARN_ON_ONCE(iomap.offset + iomap.length < pos + PAGE_SIZE)) > { > > - error = -EIO; /* fs corruption? */ > > - goto error_finish_iomap; > > + ret = VM_FAULT_SIGBUS; /* fs corruption? */ > > + goto finish_iomap; > > } > > > > if (vmf->cow_page) { > > @@ -1363,49 +1475,19 @@ static vm_fault_t dax_iomap_pte_fault(struct > vm_fault *vmf, pfn_t *pfnp, > > goto finish_iomap; > > } > > > > - sync = dax_fault_is_synchronous(flags, vma, &iomap); > > - > > - switch (iomap.type) { > > - case IOMAP_MAPPED: > > - if (iomap.flags & IOMAP_F_NEW) { > > - count_vm_event(PGMAJFAULT); > > - count_memcg_event_mm(vma->vm_mm, PGMAJFAULT); > > - major = VM_FAULT_MAJOR; > > - } > > - error = dax_iomap_pfn(&iomap, pos, PAGE_SIZE, &pfn); > > - if (error < 0) > > - goto error_finish_iomap; > > - > > - entry = dax_insert_entry(&xas, mapping, vmf, entry, pfn, > > - 0, write && !sync); > > - > > - if (sync) { > > - ret = dax_fault_synchronous_pfnp(pfnp, pfn); > > - goto finish_iomap; > > - } > > - trace_dax_insert_mapping(inode, vmf, entry); > > - if (write) > > - ret = vmf_insert_mixed_mkwrite(vma, vaddr, pfn); > > - else > > - ret = vmf_insert_mixed(vma, vaddr, pfn); > > - > > + ret = dax_fault_actor(vmf, pfnp, &xas, entry, false, flags, > > + &iomap, &srcmap); > > + if (ret == VM_FAULT_SIGBUS) > > goto finish_iomap; > > - case IOMAP_UNWRITTEN: > > - case IOMAP_HOLE: > > - if (!write) { > > - ret = dax_load_hole(&xas, mapping, &entry, vmf); > > - goto finish_iomap; > > - } > > - fallthrough; > > - default: > > - WARN_ON_ONCE(1); > > - error = -EIO; > > - break; > > + > > + /* read/write MAPPED, CoW UNWRITTEN */ > > + if (iomap.flags & IOMAP_F_NEW) { > > + count_vm_event(PGMAJFAULT); > > + count_memcg_event_mm(vma->vm_mm, PGMAJFAULT); > > + major = VM_FAULT_MAJOR; > > } > > It is much better if above accounting is also done in dax_fault_actor() > function itself. Then at the end of this function we need to just do > "return ret" instead of "return ret | major" > Yes. -- Thanks, Ruan Shiyang. > > > > > - error_finish_iomap: > > - ret = dax_fault_return(error); > > - finish_iomap: > > +finish_iomap: > > if (ops->iomap_end) { > > int copied = PAGE_SIZE; > > > > @@ -1419,66 +1501,14 @@ static vm_fault_t dax_iomap_pte_fault(struct > vm_fault *vmf, pfn_t *pfnp, > > */ > > ops->iomap_end(inode, pos, PAGE_SIZE, copied, flags, &iomap); > > } > > - unlock_entry: > > +unlock_entry: > > dax_unlock_entry(&xas, entry); > > - out: > > +out: > > trace_dax_pte_fault_done(inode, vmf, ret); > > return ret | major; > > } > > > -ritesh
> + if (!pmd) > + return dax_load_hole(xas, mapping, &entry, vmf); > + else > + return dax_pmd_load_hole(xas, vmf, iomap, &entry); > + if (pmd) > + return vmf_insert_pfn_pmd(vmf, pfn, write); > + if (write) > + return vmf_insert_mixed_mkwrite(vmf->vma, vmf->address, pfn); > + else > + return vmf_insert_mixed(vmf->vma, vmf->address, pfn); > +} No need for else statements after returning. Otherwise looks good: Reviewed-by: Christoph Hellwig <hch@lst.de>
diff --git a/fs/dax.c b/fs/dax.c index 7031e4302b13..33ddad0f3091 100644 --- a/fs/dax.c +++ b/fs/dax.c @@ -1053,6 +1053,66 @@ static vm_fault_t dax_load_hole(struct xa_state *xas, return ret; } +#ifdef CONFIG_FS_DAX_PMD +static vm_fault_t dax_pmd_load_hole(struct xa_state *xas, struct vm_fault *vmf, + struct iomap *iomap, void **entry) +{ + struct address_space *mapping = vmf->vma->vm_file->f_mapping; + unsigned long pmd_addr = vmf->address & PMD_MASK; + struct vm_area_struct *vma = vmf->vma; + struct inode *inode = mapping->host; + pgtable_t pgtable = NULL; + struct page *zero_page; + spinlock_t *ptl; + pmd_t pmd_entry; + pfn_t pfn; + + zero_page = mm_get_huge_zero_page(vmf->vma->vm_mm); + + if (unlikely(!zero_page)) + goto fallback; + + pfn = page_to_pfn_t(zero_page); + *entry = dax_insert_entry(xas, mapping, vmf, *entry, pfn, + DAX_PMD | DAX_ZERO_PAGE, false); + + if (arch_needs_pgtable_deposit()) { + pgtable = pte_alloc_one(vma->vm_mm); + if (!pgtable) + return VM_FAULT_OOM; + } + + ptl = pmd_lock(vmf->vma->vm_mm, vmf->pmd); + if (!pmd_none(*(vmf->pmd))) { + spin_unlock(ptl); + goto fallback; + } + + if (pgtable) { + pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, pgtable); + mm_inc_nr_ptes(vma->vm_mm); + } + pmd_entry = mk_pmd(zero_page, vmf->vma->vm_page_prot); + pmd_entry = pmd_mkhuge(pmd_entry); + set_pmd_at(vmf->vma->vm_mm, pmd_addr, vmf->pmd, pmd_entry); + spin_unlock(ptl); + trace_dax_pmd_load_hole(inode, vmf, zero_page, *entry); + return VM_FAULT_NOPAGE; + +fallback: + if (pgtable) + pte_free(vma->vm_mm, pgtable); + trace_dax_pmd_load_hole_fallback(inode, vmf, zero_page, *entry); + return VM_FAULT_FALLBACK; +} +#else +static vm_fault_t dax_pmd_load_hole(struct xa_state *xas, struct vm_fault *vmf, + struct iomap *iomap, void **entry) +{ + return VM_FAULT_FALLBACK; +} +#endif /* CONFIG_FS_DAX_PMD */ + s64 dax_iomap_zero(loff_t pos, u64 length, struct iomap *iomap) { sector_t sector = iomap_sector(iomap, pos & PAGE_MASK); @@ -1289,6 +1349,61 @@ static int dax_fault_cow_page(struct vm_fault *vmf, struct iomap *iomap, return 0; } +/** + * dax_fault_actor - Common actor to handle pfn insertion in PTE/PMD fault. + * @vmf: vm fault instance + * @pfnp: pfn to be returned + * @xas: the dax mapping tree of a file + * @entry: an unlocked dax entry to be inserted + * @pmd: distinguish whether it is a pmd fault + * @flags: iomap flags + * @iomap: from iomap_begin() + * @srcmap: from iomap_begin(), not equal to iomap if it is a CoW + */ +static vm_fault_t dax_fault_actor(struct vm_fault *vmf, pfn_t *pfnp, + struct xa_state *xas, void *entry, bool pmd, unsigned int flags, + struct iomap *iomap, struct iomap *srcmap) +{ + struct address_space *mapping = vmf->vma->vm_file->f_mapping; + size_t size = pmd ? PMD_SIZE : PAGE_SIZE; + loff_t pos = (loff_t)xas->xa_offset << PAGE_SHIFT; + bool write = vmf->flags & FAULT_FLAG_WRITE; + bool sync = dax_fault_is_synchronous(flags, vmf->vma, iomap); + int err = 0; + pfn_t pfn; + + /* if we are reading UNWRITTEN and HOLE, return a hole. */ + if (!write && + (iomap->type == IOMAP_UNWRITTEN || iomap->type == IOMAP_HOLE)) { + if (!pmd) + return dax_load_hole(xas, mapping, &entry, vmf); + else + return dax_pmd_load_hole(xas, vmf, iomap, &entry); + } + + if (iomap->type != IOMAP_MAPPED) { + WARN_ON_ONCE(1); + return VM_FAULT_SIGBUS; + } + + err = dax_iomap_pfn(iomap, pos, size, &pfn); + if (err) + return dax_fault_return(err); + + entry = dax_insert_entry(xas, mapping, vmf, entry, pfn, 0, + write && !sync); + + if (sync) + return dax_fault_synchronous_pfnp(pfnp, pfn); + + if (pmd) + return vmf_insert_pfn_pmd(vmf, pfn, write); + if (write) + return vmf_insert_mixed_mkwrite(vmf->vma, vmf->address, pfn); + else + return vmf_insert_mixed(vmf->vma, vmf->address, pfn); +} + static vm_fault_t dax_iomap_pte_fault(struct vm_fault *vmf, pfn_t *pfnp, int *iomap_errp, const struct iomap_ops *ops) { @@ -1296,17 +1411,14 @@ static vm_fault_t dax_iomap_pte_fault(struct vm_fault *vmf, pfn_t *pfnp, struct address_space *mapping = vma->vm_file->f_mapping; XA_STATE(xas, &mapping->i_pages, vmf->pgoff); struct inode *inode = mapping->host; - unsigned long vaddr = vmf->address; loff_t pos = (loff_t)vmf->pgoff << PAGE_SHIFT; struct iomap iomap = { .type = IOMAP_HOLE }; struct iomap srcmap = { .type = IOMAP_HOLE }; unsigned flags = IOMAP_FAULT; int error, major = 0; bool write = vmf->flags & FAULT_FLAG_WRITE; - bool sync; vm_fault_t ret = 0; void *entry; - pfn_t pfn; trace_dax_pte_fault(inode, vmf, ret); /* @@ -1352,8 +1464,8 @@ static vm_fault_t dax_iomap_pte_fault(struct vm_fault *vmf, pfn_t *pfnp, goto unlock_entry; } if (WARN_ON_ONCE(iomap.offset + iomap.length < pos + PAGE_SIZE)) { - error = -EIO; /* fs corruption? */ - goto error_finish_iomap; + ret = VM_FAULT_SIGBUS; /* fs corruption? */ + goto finish_iomap; } if (vmf->cow_page) { @@ -1363,49 +1475,19 @@ static vm_fault_t dax_iomap_pte_fault(struct vm_fault *vmf, pfn_t *pfnp, goto finish_iomap; } - sync = dax_fault_is_synchronous(flags, vma, &iomap); - - switch (iomap.type) { - case IOMAP_MAPPED: - if (iomap.flags & IOMAP_F_NEW) { - count_vm_event(PGMAJFAULT); - count_memcg_event_mm(vma->vm_mm, PGMAJFAULT); - major = VM_FAULT_MAJOR; - } - error = dax_iomap_pfn(&iomap, pos, PAGE_SIZE, &pfn); - if (error < 0) - goto error_finish_iomap; - - entry = dax_insert_entry(&xas, mapping, vmf, entry, pfn, - 0, write && !sync); - - if (sync) { - ret = dax_fault_synchronous_pfnp(pfnp, pfn); - goto finish_iomap; - } - trace_dax_insert_mapping(inode, vmf, entry); - if (write) - ret = vmf_insert_mixed_mkwrite(vma, vaddr, pfn); - else - ret = vmf_insert_mixed(vma, vaddr, pfn); - + ret = dax_fault_actor(vmf, pfnp, &xas, entry, false, flags, + &iomap, &srcmap); + if (ret == VM_FAULT_SIGBUS) goto finish_iomap; - case IOMAP_UNWRITTEN: - case IOMAP_HOLE: - if (!write) { - ret = dax_load_hole(&xas, mapping, &entry, vmf); - goto finish_iomap; - } - fallthrough; - default: - WARN_ON_ONCE(1); - error = -EIO; - break; + + /* read/write MAPPED, CoW UNWRITTEN */ + if (iomap.flags & IOMAP_F_NEW) { + count_vm_event(PGMAJFAULT); + count_memcg_event_mm(vma->vm_mm, PGMAJFAULT); + major = VM_FAULT_MAJOR; } - error_finish_iomap: - ret = dax_fault_return(error); - finish_iomap: +finish_iomap: if (ops->iomap_end) { int copied = PAGE_SIZE; @@ -1419,66 +1501,14 @@ static vm_fault_t dax_iomap_pte_fault(struct vm_fault *vmf, pfn_t *pfnp, */ ops->iomap_end(inode, pos, PAGE_SIZE, copied, flags, &iomap); } - unlock_entry: +unlock_entry: dax_unlock_entry(&xas, entry); - out: +out: trace_dax_pte_fault_done(inode, vmf, ret); return ret | major; } #ifdef CONFIG_FS_DAX_PMD -static vm_fault_t dax_pmd_load_hole(struct xa_state *xas, struct vm_fault *vmf, - struct iomap *iomap, void **entry) -{ - struct address_space *mapping = vmf->vma->vm_file->f_mapping; - unsigned long pmd_addr = vmf->address & PMD_MASK; - struct vm_area_struct *vma = vmf->vma; - struct inode *inode = mapping->host; - pgtable_t pgtable = NULL; - struct page *zero_page; - spinlock_t *ptl; - pmd_t pmd_entry; - pfn_t pfn; - - zero_page = mm_get_huge_zero_page(vmf->vma->vm_mm); - - if (unlikely(!zero_page)) - goto fallback; - - pfn = page_to_pfn_t(zero_page); - *entry = dax_insert_entry(xas, mapping, vmf, *entry, pfn, - DAX_PMD | DAX_ZERO_PAGE, false); - - if (arch_needs_pgtable_deposit()) { - pgtable = pte_alloc_one(vma->vm_mm); - if (!pgtable) - return VM_FAULT_OOM; - } - - ptl = pmd_lock(vmf->vma->vm_mm, vmf->pmd); - if (!pmd_none(*(vmf->pmd))) { - spin_unlock(ptl); - goto fallback; - } - - if (pgtable) { - pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, pgtable); - mm_inc_nr_ptes(vma->vm_mm); - } - pmd_entry = mk_pmd(zero_page, vmf->vma->vm_page_prot); - pmd_entry = pmd_mkhuge(pmd_entry); - set_pmd_at(vmf->vma->vm_mm, pmd_addr, vmf->pmd, pmd_entry); - spin_unlock(ptl); - trace_dax_pmd_load_hole(inode, vmf, zero_page, *entry); - return VM_FAULT_NOPAGE; - -fallback: - if (pgtable) - pte_free(vma->vm_mm, pgtable); - trace_dax_pmd_load_hole_fallback(inode, vmf, zero_page, *entry); - return VM_FAULT_FALLBACK; -} - static bool dax_fault_check_fallback(struct vm_fault *vmf, struct xa_state *xas, pgoff_t max_pgoff) { @@ -1519,17 +1549,15 @@ static vm_fault_t dax_iomap_pmd_fault(struct vm_fault *vmf, pfn_t *pfnp, struct address_space *mapping = vma->vm_file->f_mapping; XA_STATE_ORDER(xas, &mapping->i_pages, vmf->pgoff, PMD_ORDER); bool write = vmf->flags & FAULT_FLAG_WRITE; - bool sync; - unsigned int iomap_flags = (write ? IOMAP_WRITE : 0) | IOMAP_FAULT; + unsigned int flags = (write ? IOMAP_WRITE : 0) | IOMAP_FAULT; struct inode *inode = mapping->host; - vm_fault_t result = VM_FAULT_FALLBACK; + vm_fault_t ret = VM_FAULT_FALLBACK; struct iomap iomap = { .type = IOMAP_HOLE }; struct iomap srcmap = { .type = IOMAP_HOLE }; pgoff_t max_pgoff; void *entry; loff_t pos; int error; - pfn_t pfn; /* * Check whether offset isn't beyond end of file now. Caller is @@ -1541,7 +1569,7 @@ static vm_fault_t dax_iomap_pmd_fault(struct vm_fault *vmf, pfn_t *pfnp, trace_dax_pmd_fault(inode, vmf, max_pgoff, 0); if (xas.xa_index >= max_pgoff) { - result = VM_FAULT_SIGBUS; + ret = VM_FAULT_SIGBUS; goto out; } @@ -1556,7 +1584,7 @@ static vm_fault_t dax_iomap_pmd_fault(struct vm_fault *vmf, pfn_t *pfnp, */ entry = grab_mapping_entry(&xas, mapping, PMD_ORDER); if (xa_is_internal(entry)) { - result = xa_to_internal(entry); + ret = xa_to_internal(entry); goto fallback; } @@ -1568,7 +1596,7 @@ static vm_fault_t dax_iomap_pmd_fault(struct vm_fault *vmf, pfn_t *pfnp, */ if (!pmd_none(*vmf->pmd) && !pmd_trans_huge(*vmf->pmd) && !pmd_devmap(*vmf->pmd)) { - result = 0; + ret = 0; goto unlock_entry; } @@ -1578,49 +1606,21 @@ static vm_fault_t dax_iomap_pmd_fault(struct vm_fault *vmf, pfn_t *pfnp, * to look up our filesystem block. */ pos = (loff_t)xas.xa_index << PAGE_SHIFT; - error = ops->iomap_begin(inode, pos, PMD_SIZE, iomap_flags, &iomap, - &srcmap); + error = ops->iomap_begin(inode, pos, PMD_SIZE, flags, &iomap, &srcmap); if (error) goto unlock_entry; if (iomap.offset + iomap.length < pos + PMD_SIZE) goto finish_iomap; - sync = dax_fault_is_synchronous(iomap_flags, vma, &iomap); - - switch (iomap.type) { - case IOMAP_MAPPED: - error = dax_iomap_pfn(&iomap, pos, PMD_SIZE, &pfn); - if (error < 0) - goto finish_iomap; + ret = dax_fault_actor(vmf, pfnp, &xas, entry, true, flags, + &iomap, &srcmap); - entry = dax_insert_entry(&xas, mapping, vmf, entry, pfn, - DAX_PMD, write && !sync); - - if (sync) { - result = dax_fault_synchronous_pfnp(pfnp, pfn); - goto finish_iomap; - } - - trace_dax_pmd_insert_mapping(inode, vmf, PMD_SIZE, pfn, entry); - result = vmf_insert_pfn_pmd(vmf, pfn, write); - break; - case IOMAP_UNWRITTEN: - case IOMAP_HOLE: - if (WARN_ON_ONCE(write)) - break; - result = dax_pmd_load_hole(&xas, vmf, &iomap, &entry); - break; - default: - WARN_ON_ONCE(1); - break; - } - - finish_iomap: +finish_iomap: if (ops->iomap_end) { int copied = PMD_SIZE; - if (result == VM_FAULT_FALLBACK) + if (ret == VM_FAULT_FALLBACK) copied = 0; /* * The fault is done by now and there's no way back (other @@ -1628,19 +1628,18 @@ static vm_fault_t dax_iomap_pmd_fault(struct vm_fault *vmf, pfn_t *pfnp, * Just ignore error from ->iomap_end since we cannot do much * with it. */ - ops->iomap_end(inode, pos, PMD_SIZE, copied, iomap_flags, - &iomap); + ops->iomap_end(inode, pos, PMD_SIZE, copied, flags, &iomap); } - unlock_entry: +unlock_entry: dax_unlock_entry(&xas, entry); - fallback: - if (result == VM_FAULT_FALLBACK) { +fallback: + if (ret == VM_FAULT_FALLBACK) { split_huge_pmd(vma, vmf->pmd, vmf->address); count_vm_event(THP_FAULT_FALLBACK); } out: - trace_dax_pmd_fault_done(inode, vmf, max_pgoff, result); - return result; + trace_dax_pmd_fault_done(inode, vmf, max_pgoff, ret); + return ret; } #else static vm_fault_t dax_iomap_pmd_fault(struct vm_fault *vmf, pfn_t *pfnp,
The core logic in the two dax page fault functions is similar. So, move the logic into a common helper function. Also, to facilitate the addition of new features, such as CoW, switch-case is no longer used to handle different iomap types. Signed-off-by: Shiyang Ruan <ruansy.fnst@fujitsu.com> --- fs/dax.c | 291 +++++++++++++++++++++++++++---------------------------- 1 file changed, 145 insertions(+), 146 deletions(-)