diff options
| -rw-r--r-- | fs/dax.c | 65 |
1 files changed, 57 insertions, 8 deletions
@@ -558,6 +558,24 @@ EXPORT_SYMBOL_GPL(dax_fault); */ #define PG_PMD_COLOUR ((PMD_SIZE >> PAGE_SHIFT) - 1) +static void __dax_dbg(struct buffer_head *bh, unsigned long address, + const char *reason, const char *fn) +{ + 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") + 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) @@ -581,21 +599,29 @@ 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(NULL, address, "cow write"); return VM_FAULT_FALLBACK; } /* If the PMD would extend outside the VMA */ - if (pmd_addr < vma->vm_start) + if (pmd_addr < vma->vm_start) { + dax_pmd_dbg(NULL, address, "vma start unaligned"); return VM_FAULT_FALLBACK; - if ((pmd_addr + PMD_SIZE) > vma->vm_end) + } + if ((pmd_addr + PMD_SIZE) > vma->vm_end) { + dax_pmd_dbg(NULL, address, "vma end unaligned"); return VM_FAULT_FALLBACK; + } pgoff = linear_page_index(vma, pmd_addr); size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT; if (pgoff >= size) return VM_FAULT_SIGBUS; /* If the PMD would cover blocks out of the file */ - if ((pgoff | PG_PMD_COLOUR) >= size) + if ((pgoff | PG_PMD_COLOUR) >= size) { + dax_pmd_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); @@ -611,8 +637,10 @@ int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address, * just fall back to PTEs. Calling get_block 512 times in a loop * would be silly. */ - if (!buffer_size_valid(&bh) || bh.b_size < PMD_SIZE) + if (!buffer_size_valid(&bh) || bh.b_size < PMD_SIZE) { + dax_pmd_dbg(&bh, address, "allocated block too small"); goto fallback; + } /* * If we allocated new storage, make sure no process has any @@ -635,23 +663,33 @@ int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address, result = VM_FAULT_SIGBUS; goto out; } - if ((pgoff | PG_PMD_COLOUR) >= size) + if ((pgoff | PG_PMD_COLOUR) >= size) { + dax_pmd_dbg(&bh, address, "pgoff unaligned"); goto fallback; + } if (!write && !buffer_mapped(&bh) && buffer_uptodate(&bh)) { spinlock_t *ptl; pmd_t entry; struct page *zero_page = get_huge_zero_page(); - if (unlikely(!zero_page)) + if (unlikely(!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(&bh, address, "pmd already present"); goto fallback; } + dev_dbg(part_to_dev(bdev->bd_part), + "%s: %s addr: %lx pfn: <zero> sect: %llx\n", + __func__, current->comm, address, + (unsigned long long) to_sector(&bh, inode)); + entry = mk_pmd(zero_page, vma->vm_page_prot); entry = pmd_mkhuge(entry); set_pmd_at(vma->vm_mm, pmd_addr, pmd, entry); @@ -668,8 +706,13 @@ int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address, result = VM_FAULT_SIGBUS; goto out; } - if (length < PMD_SIZE - || (pfn_t_to_pfn(dax.pfn) & PG_PMD_COLOUR)) { + if (length < PMD_SIZE) { + 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(&bh, address, "pfn unaligned"); dax_unmap_atomic(bdev, &dax); goto fallback; } @@ -680,6 +723,7 @@ int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address, */ if (pfn_t_has_page(dax.pfn)) { dax_unmap_atomic(bdev, &dax); + dax_pmd_dbg(&bh, address, "pfn not in memmap"); goto fallback; } @@ -692,6 +736,11 @@ int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address, } 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_pmd(vma, address, pmd, dax.pfn, write); } |