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 [<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 ]--- Fixes: 5a023cdb ("block: enable dax for raw block devices") Reported-by:Dmitry Vyukov <dvyukov@google.com> Reported-by:
Kirill A. Shutemov <kirill@shutemov.name> Suggested-by:
Jan Kara <jack@suse.cz> Reviewed-by:
Jan Kara <jack@suse.cz> Suggested-by:
Matthew Wilcox <willy@linux.intel.com> Tested-by:
Ross Zwisler <ross.zwisler@linux.intel.com> Signed-off-by:
Dan Williams <dan.j.williams@intel.com>
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