As it is currently written ext4_dax_mkwrite() assumes that the call into
__dax_mkwrite() will not have to do a block allocation so it doesn't create
a journal entry. For a read that creates a zero page to cover a hole
followed by a write that actually allocates storage this is incorrect. The
ext4_dax_mkwrite() -> __dax_mkwrite() -> __dax_fault() path calls
get_blocks() to allocate storage.
Fix this by having the ->page_mkwrite fault handler call ext4_dax_fault()
as this function already has all the logic needed to allocate a journal
entry and call __dax_fault().
Also update the ext2 fault handlers in this same way to remove duplicate
code and keep the logic between ext2 and ext4 the same.
Signed-off-by: Ross Zwisler <ross.zwisler@xxxxxxxxxxxxxxx>
---
fs/ext2/file.c | 19 +------------------
fs/ext4/file.c | 19 ++-----------------
2 files changed, 3 insertions(+), 35 deletions(-)
diff --git a/fs/ext2/file.c b/fs/ext2/file.c
index 2c88d68..c1400b1 100644
--- a/fs/ext2/file.c
+++ b/fs/ext2/file.c
@@ -80,23 +80,6 @@ static int ext2_dax_pmd_fault(struct vm_area_struct *vma, unsigned long addr,
return ret;
}
-static int ext2_dax_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
-{
- struct inode *inode = file_inode(vma->vm_file);
- struct ext2_inode_info *ei = EXT2_I(inode);
- int ret;
-
- sb_start_pagefault(inode->i_sb);
- file_update_time(vma->vm_file);
- down_read(&ei->dax_sem);
-
- ret = __dax_mkwrite(vma, vmf, ext2_get_block, NULL);
-
- up_read(&ei->dax_sem);
- sb_end_pagefault(inode->i_sb);
- return ret;
-}
-
static int ext2_dax_pfn_mkwrite(struct vm_area_struct *vma,
struct vm_fault *vmf)
{
@@ -124,7 +107,7 @@ static int ext2_dax_pfn_mkwrite(struct vm_area_struct *vma,
static const struct vm_operations_struct ext2_dax_vm_ops = {
.fault = ext2_dax_fault,
.pmd_fault = ext2_dax_pmd_fault,
- .page_mkwrite = ext2_dax_mkwrite,
+ .page_mkwrite = ext2_dax_fault,
.pfn_mkwrite = ext2_dax_pfn_mkwrite,
};
diff --git a/fs/ext4/file.c b/fs/ext4/file.c
index 1126436..d2e8500 100644
--- a/fs/ext4/file.c
+++ b/fs/ext4/file.c
@@ -262,23 +262,8 @@ static int ext4_dax_pmd_fault(struct vm_area_struct *vma, unsigned long addr,
return result;
}
-static int ext4_dax_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
-{
- int err;
- struct inode *inode = file_inode(vma->vm_file);
-
- sb_start_pagefault(inode->i_sb);
- file_update_time(vma->vm_file);
- down_read(&EXT4_I(inode)->i_mmap_sem);
- err = __dax_mkwrite(vma, vmf, ext4_dax_mmap_get_block, NULL);
- up_read(&EXT4_I(inode)->i_mmap_sem);
- sb_end_pagefault(inode->i_sb);
-
- return err;
-}
-
/*
- * Handle write fault for VM_MIXEDMAP mappings. Similarly to ext4_dax_mkwrite()
+ * Handle write fault for VM_MIXEDMAP mappings. Similarly to ext4_dax_fault()
* handler we check for races agaist truncate. Note that since we cycle through
* i_mmap_sem, we are sure that also any hole punching that began before we
* were called is finished by now and so if it included part of the file we
@@ -311,7 +296,7 @@ static int ext4_dax_pfn_mkwrite(struct vm_area_struct *vma,
static const struct vm_operations_struct ext4_dax_vm_ops = {
.fault = ext4_dax_fault,
.pmd_fault = ext4_dax_pmd_fault,
- .page_mkwrite = ext4_dax_mkwrite,
+ .page_mkwrite = ext4_dax_fault,
.pfn_mkwrite = ext4_dax_pfn_mkwrite,
};
#else
--
2.5.0
--
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