1 files changed, 37 insertions, 2 deletions

diff --git a/fs/dax.c b/fs/dax.c
index efc210ff6665..bb9ff907738c 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -1091,6 +1091,7 @@ static int dax_iomap_pte_fault(struct vm_fault *vmf, pfn_t *pfnp,
         unsigned flags = IOMAP_FAULT;
         int error, major = 0;
         bool write = vmf->flags & FAULT_FLAG_WRITE;
+        bool sync;
         int vmf_ret = 0;
         void *entry;
         pfn_t pfn;
@@ -1169,6 +1170,8 @@ static int dax_iomap_pte_fault(struct vm_fault *vmf, pfn_t *pfnp,
                 goto finish_iomap;
         }
 
+        sync = (vma->vm_flags & VM_SYNC) && (iomap.flags & IOMAP_F_DIRTY);
+
         switch (iomap.type) {
         case IOMAP_MAPPED:
                 if (iomap.flags & IOMAP_F_NEW) {
@@ -1182,12 +1185,27 @@ static int dax_iomap_pte_fault(struct vm_fault *vmf, pfn_t *pfnp,
 
                 entry = dax_insert_mapping_entry(mapping, vmf, entry,
                                                  dax_iomap_sector(&iomap, pos),
-                                                 0, write);
+                                                 0, write && !sync);
                 if (IS_ERR(entry)) {
                         error = PTR_ERR(entry);
                         goto error_finish_iomap;
                 }
 
+                /*
+                 * If we are doing synchronous page fault and inode needs fsync,
+                 * we can insert PTE into page tables only after that happens.
+                 * Skip insertion for now and return the pfn so that caller can
+                 * insert it after fsync is done.
+                 */
+                if (sync) {
+                        if (WARN_ON_ONCE(!pfnp)) {
+                                error = -EIO;
+                                goto error_finish_iomap;
+                        }
+                        *pfnp = pfn;
+                        vmf_ret = VM_FAULT_NEEDDSYNC | major;
+                        goto finish_iomap;
+                }
                 trace_dax_insert_mapping(inode, vmf, entry);
                 if (write)
                         error = vm_insert_mixed_mkwrite(vma, vaddr, pfn);
@@ -1287,6 +1305,7 @@ static int dax_iomap_pmd_fault(struct vm_fault *vmf, pfn_t *pfnp,
         struct address_space *mapping = vma->vm_file->f_mapping;
         unsigned long pmd_addr = vmf->address & PMD_MASK;
         bool write = vmf->flags & FAULT_FLAG_WRITE;
+        bool sync;
         unsigned int iomap_flags = (write ? IOMAP_WRITE : 0) | IOMAP_FAULT;
         struct inode *inode = mapping->host;
         int result = VM_FAULT_FALLBACK;
@@ -1371,6 +1390,8 @@ static int dax_iomap_pmd_fault(struct vm_fault *vmf, pfn_t *pfnp,
         if (iomap.offset + iomap.length < pos + PMD_SIZE)
                 goto finish_iomap;
 
+        sync = (vma->vm_flags & VM_SYNC) && (iomap.flags & IOMAP_F_DIRTY);
+
         switch (iomap.type) {
         case IOMAP_MAPPED:
                 error = dax_iomap_pfn(&iomap, pos, PMD_SIZE, &pfn);
@@ -1379,10 +1400,24 @@ static int dax_iomap_pmd_fault(struct vm_fault *vmf, pfn_t *pfnp,
 
                 entry = dax_insert_mapping_entry(mapping, vmf, entry,
                                                 dax_iomap_sector(&iomap, pos),
-                                                RADIX_DAX_PMD, write);
+                                                RADIX_DAX_PMD, write && !sync);
                 if (IS_ERR(entry))
                         goto finish_iomap;
 
+                /*
+                 * If we are doing synchronous page fault and inode needs fsync,
+                 * we can insert PMD into page tables only after that happens.
+                 * Skip insertion for now and return the pfn so that caller can
+                 * insert it after fsync is done.
+                 */
+                if (sync) {
+                        if (WARN_ON_ONCE(!pfnp))
+                                goto finish_iomap;
+                        *pfnp = pfn;
+                        result = VM_FAULT_NEEDDSYNC;
+                        goto finish_iomap;
+                }
+
                 trace_dax_pmd_insert_mapping(inode, vmf, PMD_SIZE, pfn, entry);
                 result = vmf_insert_pfn_pmd(vma, vmf->address, vmf->pmd, pfn,
                                             write);