From: Matthew Wilcox <[email protected]> The DAX support for transparent huge PUD pages
Signed-off-by: Matthew Wilcox <[email protected]> --- fs/dax.c | 221 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++------ 1 file changed, 203 insertions(+), 18 deletions(-) diff --git a/fs/dax.c b/fs/dax.c index b82831a..0a841b6 100644 --- a/fs/dax.c +++ b/fs/dax.c @@ -513,14 +513,24 @@ static int dax_pte_fault(struct vm_area_struct *vma, struct vm_fault *vmf, */ #define PG_PMD_COLOUR ((PMD_SIZE >> PAGE_SHIFT) - 1) -static void dax_pmd_dbg(struct block_device *bdev, unsigned long address, - const char *reason) +static void __dax_dbg(struct buffer_head *bh, unsigned long address, + const char *reason, const char *fn) { - pr_debug("%s%s dax_pmd: %s addr: %lx fallback: %s\n", bdev - ? dev_name(part_to_dev(bdev->bd_part)) : "", bdev - ? ": " : "", current->comm, address, reason); + if (bh) { + char bname[BDEVNAME_SIZE]; + bdevname(bh->b_bdev, bname); + pr_debug("%s: %s addr: %lx dev %s state %lx start %lld " + "length %zd fallback: %s\n", fn, current->comm, + address, bname, bh->b_state, (u64)bh->b_blocknr, + bh->b_size, reason); + } else { + pr_debug("%s: %s addr: %lx fallback: %s\n", fn, + current->comm, address, reason); + } } +#define dax_pmd_dbg(bh, address, reason) __dax_dbg(bh, address, reason, "dax_pmd") + static int dax_pmd_fault(struct vm_area_struct *vma, unsigned long address, pmd_t *pmd, unsigned int flags, get_block_t get_block, dax_iodone_t complete_unwritten) @@ -532,7 +542,7 @@ static int dax_pmd_fault(struct vm_area_struct *vma, unsigned long address, unsigned blkbits = inode->i_blkbits; unsigned long pmd_addr = address & PMD_MASK; bool write = flags & FAULT_FLAG_WRITE; - struct block_device *bdev = NULL; + struct block_device *bdev; pgoff_t size, pgoff; sector_t block; int result = 0; @@ -544,16 +554,16 @@ static int dax_pmd_fault(struct vm_area_struct *vma, unsigned long address, /* Fall back to PTEs if we're going to COW */ if (write && !(vma->vm_flags & VM_SHARED)) { split_huge_pmd(vma, pmd, address); - dax_pmd_dbg(bdev, address, "cow write"); + dax_pmd_dbg(NULL, address, "cow write"); return VM_FAULT_FALLBACK; } /* If the PMD would extend outside the VMA */ if (pmd_addr < vma->vm_start) { - dax_pmd_dbg(bdev, address, "vma start unaligned"); + dax_pmd_dbg(NULL, address, "vma start unaligned"); return VM_FAULT_FALLBACK; } if ((pmd_addr + PMD_SIZE) > vma->vm_end) { - dax_pmd_dbg(bdev, address, "vma end unaligned"); + dax_pmd_dbg(NULL, address, "vma end unaligned"); return VM_FAULT_FALLBACK; } @@ -563,7 +573,7 @@ static int dax_pmd_fault(struct vm_area_struct *vma, unsigned long address, return VM_FAULT_SIGBUS; /* If the PMD would cover blocks out of the file */ if ((pgoff | PG_PMD_COLOUR) >= size) { - dax_pmd_dbg(bdev, address, + dax_pmd_dbg(NULL, address, "offset + huge page size > file size"); return VM_FAULT_FALLBACK; } @@ -583,7 +593,7 @@ static int dax_pmd_fault(struct vm_area_struct *vma, unsigned long address, * would be silly. */ if (!buffer_size_valid(&bh) || bh.b_size < PMD_SIZE) { - dax_pmd_dbg(bdev, address, "block allocation size invalid"); + dax_pmd_dbg(&bh, address, "allocated block too small"); goto fallback; } @@ -609,7 +619,7 @@ static int dax_pmd_fault(struct vm_area_struct *vma, unsigned long address, goto out; } if ((pgoff | PG_PMD_COLOUR) >= size) { - dax_pmd_dbg(bdev, address, "pgoff unaligned"); + dax_pmd_dbg(&bh, address, "pgoff unaligned"); goto fallback; } @@ -619,14 +629,14 @@ static int dax_pmd_fault(struct vm_area_struct *vma, unsigned long address, struct page *zero_page = get_huge_zero_page(); if (unlikely(!zero_page)) { - dax_pmd_dbg(bdev, address, "no zero page"); + dax_pmd_dbg(&bh, address, "no zero page"); goto fallback; } ptl = pmd_lock(vma->vm_mm, pmd); if (!pmd_none(*pmd)) { spin_unlock(ptl); - dax_pmd_dbg(bdev, address, "pmd already present"); + dax_pmd_dbg(&bh, address, "pmd already present"); goto fallback; } @@ -652,19 +662,19 @@ static int dax_pmd_fault(struct vm_area_struct *vma, unsigned long address, goto out; } if (length < PMD_SIZE) { - dax_pmd_dbg(bdev, address, "dax-length too small"); + dax_pmd_dbg(&bh, address, "dax-length too small"); dax_unmap_atomic(bdev, &dax); goto fallback; } if (pfn_t_to_pfn(dax.pfn) & PG_PMD_COLOUR) { - dax_pmd_dbg(bdev, address, "pfn unaligned"); + dax_pmd_dbg(&bh, address, "pfn unaligned"); dax_unmap_atomic(bdev, &dax); goto fallback; } if (!pfn_t_devmap(dax.pfn)) { dax_unmap_atomic(bdev, &dax); - dax_pmd_dbg(bdev, address, "pfn not in memmap"); + dax_pmd_dbg(&bh, address, "pfn not in memmap"); goto fallback; } @@ -708,6 +718,178 @@ static int dax_pmd_fault(struct vm_area_struct *vma, unsigned long address, } #endif /* !CONFIG_TRANSPARENT_HUGEPAGE */ +#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD +/* + * The 'colour' (ie low bits) within a PUD of a page offset. This comes up + * more often than one might expect in the below function. + */ +#define PG_PUD_COLOUR ((PUD_SIZE >> PAGE_SHIFT) - 1) + +#define dax_pud_dbg(bh, address, reason) __dax_dbg(bh, address, reason, "dax_pud") + +static int dax_pud_fault(struct vm_area_struct *vma, unsigned long address, + pud_t *pud, unsigned int flags, get_block_t get_block, + dax_iodone_t complete_unwritten) +{ + struct file *file = vma->vm_file; + struct address_space *mapping = file->f_mapping; + struct inode *inode = mapping->host; + struct buffer_head bh; + unsigned blkbits = inode->i_blkbits; + unsigned long pud_addr = address & PUD_MASK; + bool write = flags & FAULT_FLAG_WRITE; + struct block_device *bdev = NULL; + pgoff_t size, pgoff; + sector_t block; + int result = 0; + + /* dax pud mappings require pfn_t_devmap() */ + if (!IS_ENABLED(CONFIG_FS_DAX_PMD)) + return VM_FAULT_FALLBACK; + + /* Fall back to PTEs if we're going to COW */ + if (write && !(vma->vm_flags & VM_SHARED)) { + split_huge_pud(vma, pud, address); + dax_pud_dbg(NULL, address, "cow write"); + return VM_FAULT_FALLBACK; + } + /* If the PUD would extend outside the VMA */ + if (pud_addr < vma->vm_start) { + dax_pud_dbg(NULL, address, "vma start unaligned"); + return VM_FAULT_FALLBACK; + } + if ((pud_addr + PUD_SIZE) > vma->vm_end) { + dax_pud_dbg(NULL, address, "vma end unaligned"); + return VM_FAULT_FALLBACK; + } + + pgoff = linear_page_index(vma, pud_addr); + size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT; + if (pgoff >= size) + return VM_FAULT_SIGBUS; + /* If the PUD would cover blocks out of the file */ + if ((pgoff | PG_PUD_COLOUR) >= size) { + dax_pud_dbg(NULL, address, + "offset + huge page size > file size"); + return VM_FAULT_FALLBACK; + } + + memset(&bh, 0, sizeof(bh)); + block = (sector_t)pgoff << (PAGE_SHIFT - blkbits); + + bh.b_size = PUD_SIZE; + if (get_block(inode, block, &bh, write) != 0) + return VM_FAULT_SIGBUS; + bdev = bh.b_bdev; + i_mmap_lock_read(mapping); + + /* + * If the filesystem isn't willing to tell us the length of a hole, + * just fall back to PTEs. Calling get_block 512 times in a loop + * would be silly. + */ + if (!buffer_size_valid(&bh) || bh.b_size < PUD_SIZE) { + dax_pud_dbg(&bh, address, "allocated block too small"); + goto fallback; + } + + /* + * If we allocated new storage, make sure no process has any + * zero pages covering this hole + */ + if (buffer_new(&bh)) { + i_mmap_unlock_read(mapping); + unmap_mapping_range(mapping, pgoff << PAGE_SHIFT, PUD_SIZE, 0); + i_mmap_lock_read(mapping); + } + + /* + * If a truncate happened while we were allocating blocks, we may + * leave blocks allocated to the file that are beyond EOF. We can't + * take i_mutex here, so just leave them hanging; they'll be freed + * when the file is deleted. + */ + size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT; + if (pgoff >= size) { + result = VM_FAULT_SIGBUS; + goto out; + } + if ((pgoff | PG_PUD_COLOUR) >= size) { + dax_pud_dbg(&bh, address, "pgoff unaligned"); + goto fallback; + } + + if (!write && !buffer_mapped(&bh) && buffer_uptodate(&bh)) { + dax_pud_dbg(&bh, address, "no zero page"); + goto fallback; + } else { + struct blk_dax_ctl dax = { + .sector = to_sector(&bh, inode), + .size = PUD_SIZE, + }; + long length = dax_map_atomic(bdev, &dax); + + if (length < 0) { + result = VM_FAULT_SIGBUS; + goto out; + } + if (length < PUD_SIZE) { + dax_pud_dbg(&bh, address, "dax-length too small"); + dax_unmap_atomic(bdev, &dax); + goto fallback; + } + if (pfn_t_to_pfn(dax.pfn) & PG_PUD_COLOUR) { + dax_pud_dbg(&bh, address, "pfn unaligned"); + dax_unmap_atomic(bdev, &dax); + goto fallback; + } + + if (!pfn_t_devmap(dax.pfn)) { + dax_unmap_atomic(bdev, &dax); + dax_pud_dbg(&bh, address, "pfn not in memmap"); + goto fallback; + } + + if (buffer_unwritten(&bh) || buffer_new(&bh)) { + clear_pmem(dax.addr, PUD_SIZE); + wmb_pmem(); + count_vm_event(PGMAJFAULT); + mem_cgroup_count_vm_event(vma->vm_mm, PGMAJFAULT); + result |= VM_FAULT_MAJOR; + } + dax_unmap_atomic(bdev, &dax); + + dev_dbg(part_to_dev(bdev->bd_part), + "%s: %s addr: %lx pfn: %lx sect: %llx\n", + __func__, current->comm, address, + pfn_t_to_pfn(dax.pfn), + (unsigned long long) dax.sector); + result |= vmf_insert_pfn_pud(vma, address, pud, + dax.pfn, write); + } + + out: + i_mmap_unlock_read(mapping); + + if (buffer_unwritten(&bh)) + complete_unwritten(&bh, !(result & VM_FAULT_ERROR)); + + return result; + + fallback: + count_vm_event(THP_FAULT_FALLBACK); + result = VM_FAULT_FALLBACK; + goto out; +} +#else /* !CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */ +static int dax_pud_fault(struct vm_area_struct *vma, unsigned long address, + pud_t *pud, unsigned int flags, get_block_t get_block, + dax_iodone_t complete_unwritten) +{ + return VM_FAULT_FALLBACK; +} +#endif /* !CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */ + /** * dax_fault - handle a page fault on a DAX file * @vma: The virtual memory area where the fault occurred @@ -725,7 +907,7 @@ static int dax_pmd_fault(struct vm_area_struct *vma, unsigned long address, * the necessary locking for the page fault to proceed successfully. */ int dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf, - get_block_t get_block, dax_iodone_t iodone) + get_block_t get_block, dax_iodone_t iodone) { unsigned long address = (unsigned long)vmf->virtual_address; switch (vmf->flags & FAULT_FLAG_SIZE_MASK) { @@ -734,6 +916,9 @@ int dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf, case FAULT_FLAG_SIZE_PMD: return dax_pmd_fault(vma, address, vmf->pmd, vmf->flags, get_block, iodone); + case FAULT_FLAG_SIZE_PUD: + return dax_pud_fault(vma, address, vmf->pud, vmf->flags, + get_block, iodone); default: return VM_FAULT_FALLBACK; } -- 2.6.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
