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Date: Mon, 12 Jul 2021 10:28:44 +0200
From: Oleksandr Natalenko <oleksandr@...alenko.name>
To: linux-fsdevel@...r.kernel.org,
Konstantin Komarov <almaz.alexandrovich@...agon-software.com>
Cc: viro@...iv.linux.org.uk, linux-kernel@...r.kernel.org,
pali@...nel.org, dsterba@...e.cz, aaptel@...e.com,
willy@...radead.org, rdunlap@...radead.org, joe@...ches.com,
mark@...mstone.com, nborisov@...e.com,
linux-ntfs-dev@...ts.sourceforge.net, anton@...era.com,
dan.carpenter@...cle.com, hch@....de, ebiggers@...nel.org,
andy.lavr@...il.com, kari.argillander@...il.com,
Konstantin Komarov <almaz.alexandrovich@...agon-software.com>
Subject: Re: [PATCH v26 04/10] fs/ntfs3: Add file operations and implementation
Hello.
On pátek 2. dubna 2021 17:53:41 CEST Konstantin Komarov wrote:
> ...
> +/*helper for ntfs_file_write_iter (compressed files)*/
> +static ssize_t ntfs_compress_write(struct kiocb *iocb, struct iov_iter
> *from) +{
> + int err;
> + struct file *file = iocb->ki_filp;
> + size_t count = iov_iter_count(from);
> + loff_t pos = iocb->ki_pos;
> + struct inode *inode = file_inode(file);
> + loff_t i_size = inode->i_size;
> + struct address_space *mapping = inode->i_mapping;
> + struct ntfs_inode *ni = ntfs_i(inode);
> + u64 valid = ni->i_valid;
> + struct ntfs_sb_info *sbi = ni->mi.sbi;
> + struct page *page, **pages = NULL;
> + size_t written = 0;
> + u8 frame_bits = NTFS_LZNT_CUNIT + sbi->cluster_bits;
> + u32 frame_size = 1u << frame_bits;
> + u32 pages_per_frame = frame_size >> PAGE_SHIFT;
> + u32 ip, off;
> + CLST frame;
> + u64 frame_vbo;
> + pgoff_t index;
> + bool frame_uptodate;
> +
> + if (frame_size < PAGE_SIZE) {
> + /*
> + * frame_size == 8K if cluster 512
> + * frame_size == 64K if cluster 4096
> + */
> + ntfs_inode_warn(inode, "page size is bigger than frame size");
> + return -EOPNOTSUPP;
> + }
> +
> + pages = ntfs_malloc(pages_per_frame * sizeof(struct page *));
> + if (!pages)
> + return -ENOMEM;
> +
> + current->backing_dev_info = inode_to_bdi(inode);
> + err = file_remove_privs(file);
> + if (err)
> + goto out;
> +
> + err = file_update_time(file);
> + if (err)
> + goto out;
> +
> + /* zero range [valid : pos) */
> + while (valid < pos) {
> + CLST lcn, clen;
> +
> + frame = valid >> frame_bits;
> + frame_vbo = valid & ~(frame_size - 1);
> + off = valid & (frame_size - 1);
> +
> + err = attr_data_get_block(ni, frame << NTFS_LZNT_CUNIT, 0,
&lcn,
> + &clen, NULL);
> + if (err)
> + goto out;
> +
> + if (lcn == SPARSE_LCN) {
> + ni->i_valid = valid =
> + frame_vbo + ((u64)clen << sbi->cluster_bits);
> + continue;
> + }
> +
> + /* Load full frame */
> + err = ntfs_get_frame_pages(mapping, frame_vbo >> PAGE_SHIFT,
> + pages, pages_per_frame,
> + &frame_uptodate);
> + if (err)
> + goto out;
> +
> + if (!frame_uptodate && off) {
> + err = ni_read_frame(ni, frame_vbo, pages,
> + pages_per_frame);
> + if (err) {
> + for (ip = 0; ip < pages_per_frame; ip++) {
> + page = pages[ip];
> + unlock_page(page);
> + put_page(page);
> + }
> + goto out;
> + }
> + }
> +
> + ip = off >> PAGE_SHIFT;
> + off = offset_in_page(valid);
> + for (; ip < pages_per_frame; ip++, off = 0) {
> + page = pages[ip];
> + zero_user_segment(page, off, PAGE_SIZE);
> + flush_dcache_page(page);
> + SetPageUptodate(page);
> + }
> +
> + ni_lock(ni);
> + err = ni_write_frame(ni, pages, pages_per_frame);
> + ni_unlock(ni);
> +
> + for (ip = 0; ip < pages_per_frame; ip++) {
> + page = pages[ip];
> + SetPageUptodate(page);
> + unlock_page(page);
> + put_page(page);
> + }
> +
> + if (err)
> + goto out;
> +
> + ni->i_valid = valid = frame_vbo + frame_size;
> + }
> +
> + /* copy user data [pos : pos + count) */
> + while (count) {
> + size_t copied, bytes;
> +
> + off = pos & (frame_size - 1);
> + bytes = frame_size - off;
> + if (bytes > count)
> + bytes = count;
> +
> + frame = pos >> frame_bits;
> + frame_vbo = pos & ~(frame_size - 1);
> + index = frame_vbo >> PAGE_SHIFT;
> +
> + if (unlikely(iov_iter_fault_in_readable(from, bytes))) {
> + err = -EFAULT;
> + goto out;
> + }
> +
> + /* Load full frame */
> + err = ntfs_get_frame_pages(mapping, index, pages,
> + pages_per_frame, &frame_uptodate);
> + if (err)
> + goto out;
> +
> + if (!frame_uptodate) {
> + loff_t to = pos + bytes;
> +
> + if (off || (to < i_size && (to & (frame_size - 1)))) {
> + err = ni_read_frame(ni, frame_vbo, pages,
> + pages_per_frame);
> + if (err) {
> + for (ip = 0; ip < pages_per_frame;
> + ip++) {
> + page = pages[ip];
> + unlock_page(page);
> + put_page(page);
> + }
> + goto out;
> + }
> + }
> + }
> +
> + WARN_ON(!bytes);
> + copied = 0;
> + ip = off >> PAGE_SHIFT;
> + off = offset_in_page(pos);
> +
> + /* copy user data to pages */
> + for (;;) {
> + size_t cp, tail = PAGE_SIZE - off;
> +
> + page = pages[ip];
> + cp = iov_iter_copy_from_user_atomic(page, from, off,
> + min(tail, bytes));
For 5.14, iov_iter_copy_from_user_atomic() has to be replaced by
copy_page_from_iter_atomic().
> + flush_dcache_page(page);
> + iov_iter_advance(from, cp);
And iov_iter_advance() should be removed then.
Please see upstream commit f0b65f39ac505e8f1dcdaa165aa7b8c0bd6fd454 for
detailed explanation.
> + copied += cp;
> + bytes -= cp;
> + if (!bytes || !cp)
> + break;
> +
> + if (cp < tail) {
> + off += cp;
> + } else {
> + ip++;
> + off = 0;
> + }
> + }
> +
> + ni_lock(ni);
> + err = ni_write_frame(ni, pages, pages_per_frame);
> + ni_unlock(ni);
> +
> + for (ip = 0; ip < pages_per_frame; ip++) {
> + page = pages[ip];
> + ClearPageDirty(page);
> + SetPageUptodate(page);
> + unlock_page(page);
> + put_page(page);
> + }
> +
> + if (err)
> + goto out;
> +
> + /*
> + * We can loop for a long time in here. Be nice and allow
> + * us to schedule out to avoid softlocking if preempt
> + * is disabled.
> + */
> + cond_resched();
> +
> + pos += copied;
> + written += copied;
> +
> + count = iov_iter_count(from);
> + }
> +
> +out:
> + ntfs_free(pages);
> +
> + current->backing_dev_info = NULL;
> +
> + if (err < 0)
> + return err;
> +
> + iocb->ki_pos += written;
> + if (iocb->ki_pos > ni->i_valid)
> + ni->i_valid = iocb->ki_pos;
> +
> + return written;
> +}
> ...
Thanks.
--
Oleksandr Natalenko (post-factum)
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