From 65f87ee71852a754f7981d0653e7136039b8798a Mon Sep 17 00:00:00 2001 From: Dan Williams Date: Mon, 25 Jan 2016 17:23:18 -0800 Subject: [PATCH] fs, block: force direct-I/O for dax-enabled block devices Similar to the file I/O path, re-direct all I/O to the DAX path for I/O to a block-device special file. Both regular files and device special files can use the common filp->f_mapping->host lookup to determing is DAX is enabled. Otherwise, we confuse the DAX code that does not expect to find live data in the page cache: ------------[ cut here ]------------ WARNING: CPU: 0 PID: 7676 at mm/filemap.c:217 __delete_from_page_cache+0x9f6/0xb60() Modules linked in: CPU: 0 PID: 7676 Comm: a.out Not tainted 4.4.0+ #276 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 00000000ffffffff ffff88006d3f7738 ffffffff82999e2d 0000000000000000 ffff8800620a0000 ffffffff86473d20 ffff88006d3f7778 ffffffff81352089 ffffffff81658d36 ffffffff86473d20 00000000000000d9 ffffea0000009d60 Call Trace: [< inline >] __dump_stack lib/dump_stack.c:15 [] dump_stack+0x6f/0xa2 lib/dump_stack.c:50 [] warn_slowpath_common+0xd9/0x140 kernel/panic.c:482 [] warn_slowpath_null+0x29/0x30 kernel/panic.c:515 [] __delete_from_page_cache+0x9f6/0xb60 mm/filemap.c:217 [] delete_from_page_cache+0x112/0x200 mm/filemap.c:244 [] __dax_fault+0x859/0x1800 fs/dax.c:487 [] blkdev_dax_fault+0x26/0x30 fs/block_dev.c:1730 [< inline >] wp_pfn_shared mm/memory.c:2208 [] do_wp_page+0xc85/0x14f0 mm/memory.c:2307 [< inline >] handle_pte_fault mm/memory.c:3323 [< inline >] __handle_mm_fault mm/memory.c:3417 [] handle_mm_fault+0x2483/0x4640 mm/memory.c:3446 [] __do_page_fault+0x376/0x960 arch/x86/mm/fault.c:1238 [] trace_do_page_fault+0xe8/0x420 arch/x86/mm/fault.c:1331 [] do_async_page_fault+0x14/0xd0 arch/x86/kernel/kvm.c:264 [] async_page_fault+0x28/0x30 arch/x86/entry/entry_64.S:986 [] entry_SYSCALL_64_fastpath+0x16/0x7a arch/x86/entry/entry_64.S:185 ---[ end trace dae21e0f85f1f98c ]--- Fixes: 5a023cdba50c ("block: enable dax for raw block devices") Reported-by: Dmitry Vyukov Reported-by: Kirill A. Shutemov Suggested-by: Jan Kara Reviewed-by: Jan Kara Suggested-by: Matthew Wilcox Tested-by: Ross Zwisler Signed-off-by: Dan Williams --- include/linux/fs.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/include/linux/fs.h b/include/linux/fs.h index 1a2046275cdf..b10002d4a5f5 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -2907,7 +2907,7 @@ extern void replace_mount_options(struct super_block *sb, char *options); static inline bool io_is_direct(struct file *filp) { - return (filp->f_flags & O_DIRECT) || IS_DAX(file_inode(filp)); + return (filp->f_flags & O_DIRECT) || IS_DAX(filp->f_mapping->host); } static inline int iocb_flags(struct file *file) -- 2.20.1