Some ->page_mkwrite handlers may return VM_FAULT_RETRY as its return
code (GFS2 or Lustre can definitely do this). However VM_FAULT_RETRY
from ->page_mkwrite is completely unhandled by the mm code and results
in locking and writeably mapping the page which definitely is not what
the caller wanted. Fix Lustre and block_page_mkwrite_ret() used by other
filesystems (notably GFS2) to return VM_FAULT_NOPAGE instead which
results in bailing out from the fault code, the CPU then retries the
access, and we fault again effectively doing what the handler wanted.
CC: lustre-devel@xxxxxxxxxxxxxxxx
CC: cluster-devel@xxxxxxxxxx
Reported-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Jan Kara <jack@xxxxxxx>
---
drivers/staging/lustre/lustre/llite/llite_mmap.c | 4 +---
include/linux/buffer_head.h | 4 +---
2 files changed, 2 insertions(+), 6 deletions(-)
diff --git a/drivers/staging/lustre/lustre/llite/llite_mmap.c b/drivers/staging/lustre/lustre/llite/llite_mmap.c
index ee01f20d8b11..9afa6bec3e6f 100644
--- a/drivers/staging/lustre/lustre/llite/llite_mmap.c
+++ b/drivers/staging/lustre/lustre/llite/llite_mmap.c
@@ -390,15 +390,13 @@ static int ll_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
result = VM_FAULT_LOCKED;
break;
case -ENODATA:
+ case -EAGAIN:
case -EFAULT:
result = VM_FAULT_NOPAGE;
break;
case -ENOMEM:
result = VM_FAULT_OOM;
break;
- case -EAGAIN:
- result = VM_FAULT_RETRY;
- break;
default:
result = VM_FAULT_SIGBUS;
break;
diff --git a/include/linux/buffer_head.h b/include/linux/buffer_head.h
index d67ab83823ad..79591c3660cc 100644
--- a/include/linux/buffer_head.h
+++ b/include/linux/buffer_head.h
@@ -243,12 +243,10 @@ static inline int block_page_mkwrite_return(int err)
{
if (err == 0)
return VM_FAULT_LOCKED;
- if (err == -EFAULT)
+ if (err == -EFAULT || err == -EAGAIN)
return VM_FAULT_NOPAGE;
if (err == -ENOMEM)
return VM_FAULT_OOM;
- if (err == -EAGAIN)
- return VM_FAULT_RETRY;
/* -ENOSPC, -EDQUOT, -EIO ... */
return VM_FAULT_SIGBUS;
}
--
2.10.2
