diff options
| -rw-r--r-- | fs/ext4/file.c | 15 |
1 files changed, 14 insertions, 1 deletions
diff --git a/fs/ext4/file.c b/fs/ext4/file.c index 86ea1d92839a..197653ea6041 100644 --- a/fs/ext4/file.c +++ b/fs/ext4/file.c @@ -279,7 +279,20 @@ static int ext4_dax_huge_fault(struct vm_fault *vmf, handle_t *handle = NULL; struct inode *inode = file_inode(vmf->vma->vm_file); struct super_block *sb = inode->i_sb; - bool write = vmf->flags & FAULT_FLAG_WRITE; + + /* + * We have to distinguish real writes from writes which will result in a + * COW page; COW writes should *not* poke the journal (the file will not + * be changed). Doing so would cause unintended failures when mounted + * read-only. + * + * We check for VM_SHARED rather than vmf->cow_page since the latter is + * unset for pe_size != PE_SIZE_PTE (i.e. only in do_cow_fault); for + * other sizes, dax_iomap_fault will handle splitting / fallback so that + * we eventually come back with a COW page. + */ + bool write = (vmf->flags & FAULT_FLAG_WRITE) && + (vmf->vma->vm_flags & VM_SHARED); if (write) { sb_start_pagefault(sb); |