From 1e9d180ba39f42e8ca4a808baef3a3ef034b1c2c Mon Sep 17 00:00:00 2001 From: Ross Zwisler Date: Sat, 27 Feb 2016 14:01:13 -0500 Subject: [PATCH] ext2, ext4: fix issue with missing journal entry in ext4_dax_mkwrite() 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. Reviewed-by: Jan Kara Signed-off-by: Ross Zwisler Signed-off-by: Theodore Ts'o --- 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 474f1a4..4cd318f 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 -- 2.7.4