On 15.10.19 г. 21:42 ч., Omar Sandoval wrote:
> From: Omar Sandoval <osan...@fb.com>
>
> The implementation resembles direct I/O: we have to flush any ordered
> extents, invalidate the page cache, and do the io tree/delalloc/extent
> map/ordered extent dance. From there, we can reuse the compression code
> with a minor modification to distinguish the write from writeback.
>
> Now that read and write are implemented, this also sets the
> FMODE_ENCODED_IO flag in btrfs_file_open().
>
> Signed-off-by: Omar Sandoval <osan...@fb.com>
> ---
> fs/btrfs/compression.c | 6 +-
> fs/btrfs/compression.h | 5 +-
> fs/btrfs/ctree.h | 2 +
> fs/btrfs/file.c | 40 +++++++--
> fs/btrfs/inode.c | 197 ++++++++++++++++++++++++++++++++++++++++-
> 5 files changed, 237 insertions(+), 13 deletions(-)
>
> diff --git a/fs/btrfs/compression.c b/fs/btrfs/compression.c
> index b05b361e2062..6632dd8d2e4d 100644
> --- a/fs/btrfs/compression.c
> +++ b/fs/btrfs/compression.c
> @@ -276,7 +276,8 @@ static void end_compressed_bio_write(struct bio *bio)
> bio->bi_status == BLK_STS_OK);
> cb->compressed_pages[0]->mapping = NULL;
>
> - end_compressed_writeback(inode, cb);
> + if (cb->writeback)
> + end_compressed_writeback(inode, cb);
> /* note, our inode could be gone now */
>
> /*
> @@ -311,7 +312,7 @@ blk_status_t btrfs_submit_compressed_write(struct inode
> *inode, u64 start,
> unsigned long compressed_len,
> struct page **compressed_pages,
> unsigned long nr_pages,
> - unsigned int write_flags)
> + unsigned int write_flags, bool writeback)
I don't see this function being called with true in this patch set,
meaning it essentially eliminates end_compressed_writeback call in
end_compressed_bio_write? Am I missing anything?
> {
> struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
> struct bio *bio = NULL;
> @@ -336,6 +337,7 @@ blk_status_t btrfs_submit_compressed_write(struct inode
> *inode, u64 start,
> cb->mirror_num = 0;
> cb->compressed_pages = compressed_pages;
> cb->compressed_len = compressed_len;
> + cb->writeback = writeback;
> cb->orig_bio = NULL;
> cb->nr_pages = nr_pages;
>
> diff --git a/fs/btrfs/compression.h b/fs/btrfs/compression.h
> index 4cb8be9ff88b..d4176384ec15 100644
> --- a/fs/btrfs/compression.h
> +++ b/fs/btrfs/compression.h
> @@ -47,6 +47,9 @@ struct compressed_bio {
> /* the compression algorithm for this bio */
> int compress_type;
>
> + /* Whether this is a write for writeback. */
> + bool writeback;
> +
> /* number of compressed pages in the array */
> unsigned long nr_pages;
>
> @@ -93,7 +96,7 @@ blk_status_t btrfs_submit_compressed_write(struct inode
> *inode, u64 start,
> unsigned long compressed_len,
> struct page **compressed_pages,
> unsigned long nr_pages,
> - unsigned int write_flags);
> + unsigned int write_flags, bool writeback);
> blk_status_t btrfs_submit_compressed_read(struct inode *inode, struct bio
> *bio,
> int mirror_num, unsigned long bio_flags);
>
> diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
> index 3b2aa1c7218c..9e1719e82cc8 100644
> --- a/fs/btrfs/ctree.h
> +++ b/fs/btrfs/ctree.h
> @@ -2907,6 +2907,8 @@ int btrfs_writepage_cow_fixup(struct page *page, u64
> start, u64 end);
> void btrfs_writepage_endio_finish_ordered(struct page *page, u64 start,
> u64 end, int uptodate);
> ssize_t btrfs_encoded_read(struct kiocb *iocb, struct iov_iter *iter);
> +ssize_t btrfs_encoded_write(struct kiocb *iocb, struct iov_iter *from,
> + struct encoded_iov *encoded);
>
> extern const struct dentry_operations btrfs_dentry_operations;
>
> diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
> index 51740cee39fc..8de6ac9b4b9c 100644
> --- a/fs/btrfs/file.c
> +++ b/fs/btrfs/file.c
> @@ -1893,8 +1893,7 @@ static void update_time_for_write(struct inode *inode)
> inode_inc_iversion(inode);
> }
>
> -static ssize_t btrfs_file_write_iter(struct kiocb *iocb,
> - struct iov_iter *from)
> +static ssize_t btrfs_file_write_iter(struct kiocb *iocb, struct iov_iter
> *from)
> {
> struct file *file = iocb->ki_filp;
> struct inode *inode = file_inode(file);
> @@ -1904,14 +1903,22 @@ static ssize_t btrfs_file_write_iter(struct kiocb
> *iocb,
> u64 end_pos;
> ssize_t num_written = 0;
> const bool sync = iocb->ki_flags & IOCB_DSYNC;
> + struct encoded_iov encoded;
> ssize_t err;
> loff_t pos;
> size_t count;
> loff_t oldsize;
> int clean_page = 0;
>
> - if (!(iocb->ki_flags & IOCB_DIRECT) &&
> - (iocb->ki_flags & IOCB_NOWAIT))
> + if (iocb->ki_flags & IOCB_ENCODED) {
> + err = import_encoded_write(iocb, &encoded, from);
> + if (err)
> + return err;
> + }
> +
> + if ((iocb->ki_flags & IOCB_NOWAIT) &&
> + (!(iocb->ki_flags & IOCB_DIRECT) ||
> + (iocb->ki_flags & IOCB_ENCODED)))
> return -EOPNOTSUPP;
>
> if (!inode_trylock(inode)) {
> @@ -1920,14 +1927,27 @@ static ssize_t btrfs_file_write_iter(struct kiocb
> *iocb,
> inode_lock(inode);
> }
>
> - err = generic_write_checks(iocb, from);
> - if (err <= 0) {
> + if (iocb->ki_flags & IOCB_ENCODED) {
> + err = generic_encoded_write_checks(iocb, &encoded);
> + if (err) {
> + inode_unlock(inode);
> + return err;
> + }
> + count = encoded.len;
> + } else {
> + err = generic_write_checks(iocb, from);
> + if (err < 0) {
> + inode_unlock(inode);
> + return err;
> + }
> + count = iov_iter_count(from);
> + }
> + if (count == 0) {
> inode_unlock(inode);
> return err;
> }
>
> pos = iocb->ki_pos;
> - count = iov_iter_count(from);
> if (iocb->ki_flags & IOCB_NOWAIT) {
> /*
> * We will allocate space in case nodatacow is not set,
> @@ -1986,7 +2006,9 @@ static ssize_t btrfs_file_write_iter(struct kiocb *iocb,
> if (sync)
> atomic_inc(&BTRFS_I(inode)->sync_writers);
>
> - if (iocb->ki_flags & IOCB_DIRECT) {
> + if (iocb->ki_flags & IOCB_ENCODED) {
> + num_written = btrfs_encoded_write(iocb, from, &encoded);
> + } else if (iocb->ki_flags & IOCB_DIRECT) {
> num_written = __btrfs_direct_write(iocb, from);
> } else {
> num_written = btrfs_buffered_write(iocb, from);
> @@ -3461,7 +3483,7 @@ static loff_t btrfs_file_llseek(struct file *file,
> loff_t offset, int whence)
>
> static int btrfs_file_open(struct inode *inode, struct file *filp)
> {
> - filp->f_mode |= FMODE_NOWAIT;
> + filp->f_mode |= FMODE_NOWAIT | FMODE_ENCODED_IO;
> return generic_file_open(inode, filp);
> }
>
> diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
> index 174d0738d2c9..bcc5a2bed22b 100644
> --- a/fs/btrfs/inode.c
> +++ b/fs/btrfs/inode.c
> @@ -865,7 +865,7 @@ static noinline void submit_compressed_extents(struct
> async_chunk *async_chunk)
> ins.objectid,
> ins.offset, async_extent->pages,
> async_extent->nr_pages,
> - async_chunk->write_flags)) {
> + async_chunk->write_flags, true)) {
> struct page *p = async_extent->pages[0];
> const u64 start = async_extent->start;
> const u64 end = start + async_extent->ram_size - 1;
> @@ -11055,6 +11055,201 @@ ssize_t btrfs_encoded_read(struct kiocb *iocb,
> struct iov_iter *iter)
> return ret;
> }
>
> +ssize_t btrfs_encoded_write(struct kiocb *iocb, struct iov_iter *from,
> + struct encoded_iov *encoded)
> +{
> + struct inode *inode = file_inode(iocb->ki_filp);
> + struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
> + struct btrfs_root *root = BTRFS_I(inode)->root;
> + struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
> + struct extent_changeset *data_reserved = NULL;
> + struct extent_state *cached_state = NULL;
> + int compression;
> + size_t orig_count;
> + u64 disk_num_bytes, num_bytes;
> + u64 start, end;
> + unsigned long nr_pages, i;
> + struct page **pages;
> + struct btrfs_key ins;
> + struct extent_map *em;
> + ssize_t ret;
> +
> + switch (encoded->compression) {
> + case ENCODED_IOV_COMPRESSION_ZLIB:
> + compression = BTRFS_COMPRESS_ZLIB;
> + break;
> + case ENCODED_IOV_COMPRESSION_LZO:
> + compression = BTRFS_COMPRESS_LZO;
> + break;
> + case ENCODED_IOV_COMPRESSION_ZSTD:
> + compression = BTRFS_COMPRESS_ZSTD;
> + break;
> + default:
> + return -EINVAL;
> + }
> +
> + disk_num_bytes = orig_count = iov_iter_count(from);
> +
> + /* For now, it's too hard to support bookend extents. */
> + if (encoded->unencoded_len != encoded->len ||
> + encoded->unencoded_offset != 0)
> + return -EINVAL;
> +
> + /* The extent size must be sane. */
> + if (encoded->unencoded_len > BTRFS_MAX_UNCOMPRESSED ||
> + disk_num_bytes > BTRFS_MAX_COMPRESSED || disk_num_bytes == 0)
> + return -EINVAL;
> +
> + /*
> + * The compressed data on disk must be sector-aligned. For convenience,
> + * we extend it with zeroes if it isn't.
> + */
> + disk_num_bytes = ALIGN(disk_num_bytes, fs_info->sectorsize);
> +
> + /*
> + * The extent in the file must also be sector-aligned. However, we allow
> + * a write which ends at or extends i_size to have an unaligned length;
> + * we round up the extent size and set i_size to the given length.
> + */
> + start = iocb->ki_pos;
> + if (!IS_ALIGNED(start, fs_info->sectorsize))
> + return -EINVAL;
> + if (start + encoded->len >= inode->i_size) {
> + num_bytes = ALIGN(encoded->len, fs_info->sectorsize);
> + } else {
> + num_bytes = encoded->len;
> + if (!IS_ALIGNED(num_bytes, fs_info->sectorsize))
> + return -EINVAL;
> + }
> +
> + /*
> + * It's valid to have compressed data which is larger than or the same
> + * size as the decompressed data. However, for buffered I/O, we fall
> + * back to writing the decompressed data if compression didn't shrink
> + * it. So, for now, let's not allow creating such extents.
> + *
> + * Note that for now this also implicitly prevents writing data that
> + * would fit in an inline extent.
> + */
> + if (disk_num_bytes >= num_bytes)
> + return -EINVAL;
> +
> + end = start + num_bytes - 1;
> +
> + nr_pages = (disk_num_bytes + PAGE_SIZE - 1) >> PAGE_SHIFT;
nit: nr_pages = DIV_ROUND_UP(disk_num_bytes, PAGE_SIZE)
> + pages = kvcalloc(nr_pages, sizeof(struct page *), GFP_USER);
This could be a simple GFP_KERNEL allocation
> + if (!pages)
> + return -ENOMEM;
> + for (i = 0; i < nr_pages; i++) {
> + size_t bytes = min_t(size_t, PAGE_SIZE, iov_iter_count(from));
> + char *kaddr;
> +
> + pages[i] = alloc_page(GFP_HIGHUSER);
Why GFP_HIGHUSER? You are reading from userspace, not writing to it. A
plain, NOFS allocation should suffice (of course using the newer
memalloc_nofs_save api)?
> + if (!pages[i]) {
> + ret = -ENOMEM;
> + goto out_pages;
> + }
> + kaddr = kmap(pages[i]);
> + if (copy_from_iter(kaddr, bytes, from) != bytes) {
> + kunmap(pages[i]);
> + ret = -EFAULT;
> + goto out_pages;
> + }
> + if (bytes < PAGE_SIZE)
> + memset(kaddr + bytes, 0, PAGE_SIZE - bytes);
> + kunmap(pages[i]);
> + }
> +
> + for (;;) {
> + struct btrfs_ordered_extent *ordered;
> +
> + ret = btrfs_wait_ordered_range(inode, start, end - start + 1);
> + if (ret)
> + goto out_pages;
> + ret = invalidate_inode_pages2_range(inode->i_mapping,
> + start >> PAGE_SHIFT,
> + end >> PAGE_SHIFT);
> + if (ret)
> + goto out_pages;
> + lock_extent_bits(io_tree, start, end, &cached_state);
> + ordered = btrfs_lookup_ordered_range(BTRFS_I(inode), start,
> + end - start + 1);
> + if (!ordered &&
> + !filemap_range_has_page(inode->i_mapping, start, end))
> + break;
> + if (ordered)
> + btrfs_put_ordered_extent(ordered);
> + unlock_extent_cached(io_tree, start, end, &cached_state);
> + cond_resched();
> + }
> +
> + ret = btrfs_delalloc_reserve_space(inode, &data_reserved, start,
> + num_bytes);
> + if (ret)
> + goto out_unlock;
> +
> + ret = btrfs_reserve_extent(root, num_bytes, disk_num_bytes,
> + disk_num_bytes, 0, 0, &ins, 1, 1);
> + if (ret)
> + goto out_delalloc_release;
> +
> + em = create_io_em(inode, start, num_bytes, start, ins.objectid,
> + ins.offset, ins.offset, num_bytes, compression,
> + BTRFS_ORDERED_COMPRESSED);
> + if (IS_ERR(em)) {
> + ret = PTR_ERR(em);
> + goto out_free_reserve;
> + }
> + free_extent_map(em);
> +
> + ret = btrfs_add_ordered_extent_compress(inode, start, ins.objectid,
> + num_bytes, ins.offset,
> + BTRFS_ORDERED_COMPRESSED,
> + compression);
> + if (ret) {
> + btrfs_drop_extent_cache(BTRFS_I(inode), start, end, 0);
> + goto out_free_reserve;
> + }
> + btrfs_dec_block_group_reservations(fs_info, ins.objectid);
> +
> + if (start + encoded->len > inode->i_size)
> + i_size_write(inode, start + encoded->len);
Don't we want the inode size to be updated once data hits disk and
btrfs_finish_ordered_io is called?
> +
> + unlock_extent_cached(io_tree, start, end, &cached_state);
> +
> + btrfs_delalloc_release_extents(BTRFS_I(inode), num_bytes, false);
> +
> + if (btrfs_submit_compressed_write(inode, start, num_bytes, ins.objectid,
> + ins.offset, pages, nr_pages, 0,
> + false)) {
> + struct page *page = pages[0];
> +
> + page->mapping = inode->i_mapping;
> + btrfs_writepage_endio_finish_ordered(page, start, end, 0);
> + page->mapping = NULL;
> + ret = -EIO;
> + goto out_pages;
> + }
> + iocb->ki_pos += encoded->len;
> + return orig_count;
> +
> +out_free_reserve:
> + btrfs_dec_block_group_reservations(fs_info, ins.objectid);
> + btrfs_free_reserved_extent(fs_info, ins.objectid, ins.offset, 1);
> +out_delalloc_release:
> + btrfs_delalloc_release_space(inode, data_reserved, start, num_bytes,
> + true);
> +out_unlock:
> + unlock_extent_cached(io_tree, start, end, &cached_state);
> +out_pages:
> + for (i = 0; i < nr_pages; i++) {
> + if (pages[i])
> + put_page(pages[i]);
> + }
> + kvfree(pages);
> + return ret;
> +}
> +
> #ifdef CONFIG_SWAP
> /*
> * Add an entry indicating a block group or device which is pinned by a
>
