Implement a function that filesystems can call to finish handling of
synchronous page faults. It takes care of syncing appropriare file range
and insertion of page table entry.
Reviewed-by: Ross Zwisler <ross.zwisler@xxxxxxxxxxxxxxx>
Reviewed-by: Christoph Hellwig <hch@xxxxxx>
Signed-off-by: Jan Kara <jack@xxxxxxx>
---
fs/dax.c | 83 +++++++++++++++++++++++++++++++++++++++++++
include/linux/dax.h | 2 ++
include/trace/events/fs_dax.h | 2 ++
3 files changed, 87 insertions(+)
diff --git a/fs/dax.c b/fs/dax.c
index bb9ff907738c..78233c716757 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -1492,3 +1492,86 @@ int dax_iomap_fault(struct vm_fault *vmf, enum page_entry_size pe_size,
}
}
EXPORT_SYMBOL_GPL(dax_iomap_fault);
+
+/**
+ * dax_insert_pfn_mkwrite - insert PTE or PMD entry into page tables
+ * @vmf: The description of the fault
+ * @pe_size: Size of entry to be inserted
+ * @pfn: PFN to insert
+ *
+ * This function inserts writeable PTE or PMD entry into page tables for mmaped
+ * DAX file. It takes care of marking corresponding radix tree entry as dirty
+ * as well.
+ */
+static int dax_insert_pfn_mkwrite(struct vm_fault *vmf,
+ enum page_entry_size pe_size,
+ pfn_t pfn)
+{
+ struct address_space *mapping = vmf->vma->vm_file->f_mapping;
+ void *entry, **slot;
+ pgoff_t index = vmf->pgoff;
+ int vmf_ret, error;
+
+ spin_lock_irq(&mapping->tree_lock);
+ entry = get_unlocked_mapping_entry(mapping, index, &slot);
+ /* Did we race with someone splitting entry or so? */
+ if (!entry ||
+ (pe_size == PE_SIZE_PTE && !dax_is_pte_entry(entry)) ||
+ (pe_size == PE_SIZE_PMD && !dax_is_pmd_entry(entry))) {
+ put_unlocked_mapping_entry(mapping, index, entry);
+ spin_unlock_irq(&mapping->tree_lock);
+ trace_dax_insert_pfn_mkwrite_no_entry(mapping->host, vmf,
+ VM_FAULT_NOPAGE);
+ return VM_FAULT_NOPAGE;
+ }
+ radix_tree_tag_set(&mapping->page_tree, index, PAGECACHE_TAG_DIRTY);
+ entry = lock_slot(mapping, slot);
+ spin_unlock_irq(&mapping->tree_lock);
+ switch (pe_size) {
+ case PE_SIZE_PTE:
+ error = vm_insert_mixed_mkwrite(vmf->vma, vmf->address, pfn);
+ vmf_ret = dax_fault_return(error);
+ break;
+#ifdef CONFIG_FS_DAX_PMD
+ case PE_SIZE_PMD:
+ vmf_ret = vmf_insert_pfn_pmd(vmf->vma, vmf->address, vmf->pmd,
+ pfn, true);
+ break;
+#endif
+ default:
+ vmf_ret = VM_FAULT_FALLBACK;
+ }
+ put_locked_mapping_entry(mapping, index);
+ trace_dax_insert_pfn_mkwrite(mapping->host, vmf, vmf_ret);
+ return vmf_ret;
+}
+
+/**
+ * dax_finish_sync_fault - finish synchronous page fault
+ * @vmf: The description of the fault
+ * @pe_size: Size of entry to be inserted
+ * @pfn: PFN to insert
+ *
+ * This function ensures that the file range touched by the page fault is
+ * stored persistently on the media and handles inserting of appropriate page
+ * table entry.
+ */
+int dax_finish_sync_fault(struct vm_fault *vmf, enum page_entry_size pe_size,
+ pfn_t pfn)
+{
+ int err;
+ loff_t start = ((loff_t)vmf->pgoff) << PAGE_SHIFT;
+ size_t len = 0;
+
+ if (pe_size == PE_SIZE_PTE)
+ len = PAGE_SIZE;
+ else if (pe_size == PE_SIZE_PMD)
+ len = PMD_SIZE;
+ else
+ WARN_ON_ONCE(1);
+ err = vfs_fsync_range(vmf->vma->vm_file, start, start + len - 1, 1);
+ if (err)
+ return VM_FAULT_SIGBUS;
+ return dax_insert_pfn_mkwrite(vmf, pe_size, pfn);
+}
+EXPORT_SYMBOL_GPL(dax_finish_sync_fault);
diff --git a/include/linux/dax.h b/include/linux/dax.h
index e7fa4b8f45bc..d403f78b706c 100644
--- a/include/linux/dax.h
+++ b/include/linux/dax.h
@@ -96,6 +96,8 @@ ssize_t dax_iomap_rw(struct kiocb *iocb, struct iov_iter *iter,
const struct iomap_ops *ops);
int dax_iomap_fault(struct vm_fault *vmf, enum page_entry_size pe_size,
pfn_t *pfnp, const struct iomap_ops *ops);
+int dax_finish_sync_fault(struct vm_fault *vmf, enum page_entry_size pe_size,
+ pfn_t pfn);
int dax_delete_mapping_entry(struct address_space *mapping, pgoff_t index);
int dax_invalidate_mapping_entry_sync(struct address_space *mapping,
pgoff_t index);
diff --git a/include/trace/events/fs_dax.h b/include/trace/events/fs_dax.h
index 88a9d19b8ff8..7725459fafef 100644
--- a/include/trace/events/fs_dax.h
+++ b/include/trace/events/fs_dax.h
@@ -190,6 +190,8 @@ DEFINE_EVENT(dax_pte_fault_class, name, \
DEFINE_PTE_FAULT_EVENT(dax_pte_fault);
DEFINE_PTE_FAULT_EVENT(dax_pte_fault_done);
DEFINE_PTE_FAULT_EVENT(dax_load_hole);
+DEFINE_PTE_FAULT_EVENT(dax_insert_pfn_mkwrite_no_entry);
+DEFINE_PTE_FAULT_EVENT(dax_insert_pfn_mkwrite);
TRACE_EVENT(dax_insert_mapping,
TP_PROTO(struct inode *inode, struct vm_fault *vmf, void *radix_entry),
--
2.12.3
