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Date: Thu, 24 Aug 2017 09:18:19 +0200 From: Jan Kara <jack@...e.cz> To: Christoph Hellwig <hch@...radead.org> Cc: Jan Kara <jack@...e.cz>, linux-fsdevel@...r.kernel.org, Boaz Harrosh <boazh@...app.com>, linux-nvdimm@...ts.01.org, linux-xfs@...r.kernel.org, Andy Lutomirski <luto@...nel.org>, linux-ext4@...r.kernel.org Subject: Re: [PATCH 13/13] ext4: Support for synchronous DAX faults On Wed 23-08-17 11:37:14, Christoph Hellwig wrote: > > + pfn_t pfn; > > > > if (write) { > > sb_start_pagefault(sb); > > @@ -287,16 +288,39 @@ static int ext4_dax_huge_fault(struct vm_fault *vmf, > > down_read(&EXT4_I(inode)->i_mmap_sem); > > handle = ext4_journal_start_sb(sb, EXT4_HT_WRITE_PAGE, > > EXT4_DATA_TRANS_BLOCKS(sb)); > > + if (IS_ERR(handle)) { > > + up_read(&EXT4_I(inode)->i_mmap_sem); > > + sb_end_pagefault(sb); > > + return VM_FAULT_SIGBUS; > > + } > > } else { > > down_read(&EXT4_I(inode)->i_mmap_sem); > > } > > - if (!IS_ERR(handle)) > > - result = dax_iomap_fault(vmf, pe_size, &ext4_iomap_ops, NULL); > > - else > > - result = VM_FAULT_SIGBUS; > > + result = dax_iomap_fault(vmf, pe_size, &ext4_iomap_ops, &pfn); > > Maybe split the error handling refactor into a simple prep patch to > make this one more readable? OK, will do. > > + /* Write fault but PFN mapped only RO? */ > > + if (result & VM_FAULT_NEEDDSYNC) { > > + int err; > > + loff_t start = ((loff_t)vmf->pgoff) << PAGE_SHIFT; > > + size_t len = 0; > > + > > + if (pe_size == PE_SIZE_PTE) > > + len = PAGE_SIZE; > > +#ifdef CONFIG_FS_DAX_PMD > > + else if (pe_size == PE_SIZE_PMD) > > + len = HPAGE_PMD_SIZE; > > +#endif > > + else > > + WARN_ON_ONCE(1); > > + err = vfs_fsync_range(vmf->vma->vm_file, start, > > + start + len - 1, 1); > > + if (err) > > + result = VM_FAULT_SIGBUS; > > + else > > + result = dax_insert_pfn_mkwrite(vmf, pe_size, > > + pfn); > > + } > > I think this needs to become a helper exported from the DAX code, > way too much magic inside the file system as-is. Good point, there isn't anything fs specific in there. Honza -- Jan Kara <jack@...e.com> SUSE Labs, CR
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