We just need to make sure ext4_filemap_fault() doesn't block in the
speculative case as it is called with an rcu read lock held.
Signed-off-by: Michel Lespinasse <michel@xxxxxxxxxxxxxx>
---
fs/ext4/file.c | 1 +
fs/ext4/inode.c | 7 ++++++-
2 files changed, 7 insertions(+), 1 deletion(-)
diff --git a/fs/ext4/file.c b/fs/ext4/file.c
index 194f5d00fa32..546b9d4aa9d7 100644
--- a/fs/ext4/file.c
+++ b/fs/ext4/file.c
@@ -742,6 +742,7 @@ static const struct vm_operations_struct ext4_file_vm_ops = {
.fault = ext4_filemap_fault,
.map_pages = filemap_map_pages,
.page_mkwrite = ext4_page_mkwrite,
+ .speculative = true,
};
static int ext4_file_mmap(struct file *file, struct vm_area_struct *vma)
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 0948a43f1b3d..370484403c71 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -6192,7 +6192,12 @@ vm_fault_t ext4_filemap_fault(struct vm_fault *vmf)
struct inode *inode = file_inode(vmf->vma->vm_file);
vm_fault_t ret;
- down_read(&EXT4_I(inode)->i_mmap_sem);
+ if (vmf->flags & FAULT_FLAG_SPECULATIVE) {
+ if (!down_read_trylock(&EXT4_I(inode)->i_mmap_sem))
+ return VM_FAULT_RETRY;
+ } else {
+ down_read(&EXT4_I(inode)->i_mmap_sem);
+ }
ret = filemap_fault(vmf);
up_read(&EXT4_I(inode)->i_mmap_sem);
--
2.20.1
