On Mon, 2016-01-25 at 13:22 +0100, Jan Kara wrote: [..] > Thanks. Despite the huge list of recipients the author of the changes > hasn't been CCed :) I've added Dan to CC since he wrote DAX support > for > block devices. It seems somehow the write didn't go through the DAX > path > but through the standard page cache write path. Ah, I see, only > file->f_mapping->host has S_DAX set but io_is_direct() which decides > whether DAX or pagecache path should be used for writes uses file- > >f_inode > which is something different for block devices...
Thanks, yes, the following silences the warning for me: 8<----- (git am --scissors) Subject: fs, block: force direct-I/O for dax-enabled block devices From: Dan Williams <dan.j.willi...@intel.com> 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. 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 [<ffffffff82999e2d>] dump_stack+0x6f/0xa2 lib/dump_stack.c:50 [<ffffffff81352089>] warn_slowpath_common+0xd9/0x140 kernel/panic.c:482 [<ffffffff813522b9>] warn_slowpath_null+0x29/0x30 kernel/panic.c:515 [<ffffffff81658d36>] __delete_from_page_cache+0x9f6/0xb60 mm/filemap.c:217 [<ffffffff81658fb2>] delete_from_page_cache+0x112/0x200 mm/filemap.c:244 [<ffffffff818af369>] __dax_fault+0x859/0x1800 fs/dax.c:487 [<ffffffff8186f4f6>] blkdev_dax_fault+0x26/0x30 fs/block_dev.c:1730 [< inline >] wp_pfn_shared mm/memory.c:2208 [<ffffffff816e9145>] 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 [<ffffffff816ecec3>] handle_mm_fault+0x2483/0x4640 mm/memory.c:3446 [<ffffffff8127eff6>] __do_page_fault+0x376/0x960 arch/x86/mm/fault.c:1238 [<ffffffff8127f738>] trace_do_page_fault+0xe8/0x420 arch/x86/mm/fault.c:1331 [<ffffffff812705c4>] do_async_page_fault+0x14/0xd0 arch/x86/kernel/kvm.c:264 [<ffffffff86338f78>] async_page_fault+0x28/0x30 arch/x86/entry/entry_64.S:986 [<ffffffff86336c36>] entry_SYSCALL_64_fastpath+0x16/0x7a arch/x86/entry/entry_64.S:185 ---[ end trace dae21e0f85f1f98c ]--- Cc: Matthew Wilcox <wi...@linux.intel.com> Cc: Ross Zwisler <ross.zwis...@linux.intel.com> Fixes: 5a023cdba50c ("block: enable dax for raw block devices") Reported-by: Dmitry Vyukov <dvyu...@google.com> Reported-by: Kirill A. Shutemov <kir...@shutemov.name> Suggested-by: Jan Kara <j...@suse.cz> Signed-off-by: Dan Williams <dan.j.willi...@intel.com> --- fs/block_dev.c | 5 ----- include/linux/fs.h | 12 +++++++++++- 2 files changed, 11 insertions(+), 6 deletions(-) diff --git a/fs/block_dev.c b/fs/block_dev.c index 7b9cd49622b1..277008617b2d 100644 --- a/fs/block_dev.c +++ b/fs/block_dev.c @@ -156,11 +156,6 @@ blkdev_get_block(struct inode *inode, sector_t iblock, return 0; } -static struct inode *bdev_file_inode(struct file *file) -{ - return file->f_mapping->host; -} - static ssize_t blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter, loff_t offset) { diff --git a/include/linux/fs.h b/include/linux/fs.h index 1a2046275cdf..a4c4314eed48 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -1237,6 +1237,11 @@ static inline struct inode *file_inode(const struct file *f) return f->f_inode; } +static inline struct inode *bdev_file_inode(struct file *file) +{ + return file->f_mapping->host; +} + static inline int locks_lock_file_wait(struct file *filp, struct file_lock *fl) { return locks_lock_inode_wait(file_inode(filp), fl); @@ -2907,7 +2912,12 @@ 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)); + struct inode *inode = file_inode(filp); + + if (S_ISBLK(inode->i_mode)) + inode = bdev_file_inode(filp); + + return (filp->f_flags & O_DIRECT) || IS_DAX(inode); } static inline int iocb_flags(struct file *file)