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. This
also creates inline extents when possible.

Now that read and write are implemented, this also sets the
FMODE_ENCODED_IO flag in btrfs_file_open().

Reviewed-by: Josef Bacik <jo...@toxicpanda.com>
Signed-off-by: Omar Sandoval <osan...@fb.com>
---
 fs/btrfs/compression.c  |   7 +-
 fs/btrfs/compression.h  |   6 +-
 fs/btrfs/ctree.h        |   2 +
 fs/btrfs/file.c         |  38 +++++-
 fs/btrfs/inode.c        | 259 +++++++++++++++++++++++++++++++++++++++-
 fs/btrfs/ordered-data.c |  12 +-
 fs/btrfs/ordered-data.h |   2 +
 7 files changed, 314 insertions(+), 12 deletions(-)

diff --git a/fs/btrfs/compression.c b/fs/btrfs/compression.c
index d9d1d9e38fc5..4cfd03918ffc 100644
--- a/fs/btrfs/compression.c
+++ b/fs/btrfs/compression.c
@@ -336,7 +336,8 @@ 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 */
 
        /*
@@ -372,7 +373,8 @@ blk_status_t btrfs_submit_compressed_write(struct 
btrfs_inode *inode, u64 start,
                                 struct page **compressed_pages,
                                 unsigned long nr_pages,
                                 unsigned int write_flags,
-                                struct cgroup_subsys_state *blkcg_css)
+                                struct cgroup_subsys_state *blkcg_css,
+                                bool writeback)
 {
        struct btrfs_fs_info *fs_info = inode->root->fs_info;
        struct bio *bio = NULL;
@@ -396,6 +398,7 @@ blk_status_t btrfs_submit_compressed_write(struct 
btrfs_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 8001b700ea3a..f95cdc16f503 100644
--- a/fs/btrfs/compression.h
+++ b/fs/btrfs/compression.h
@@ -49,6 +49,9 @@ 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;
 
@@ -96,7 +99,8 @@ blk_status_t btrfs_submit_compressed_write(struct btrfs_inode 
*inode, u64 start,
                                  struct page **compressed_pages,
                                  unsigned long nr_pages,
                                  unsigned int write_flags,
-                                 struct cgroup_subsys_state *blkcg_css);
+                                 struct cgroup_subsys_state *blkcg_css,
+                                 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 d093f7a900d7..33a08ab5cb0e 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -3158,6 +3158,8 @@ 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_do_encoded_write(struct kiocb *iocb, struct iov_iter *from,
+                              struct encoded_iov *encoded);
 
 extern const struct dentry_operations btrfs_dentry_operations;
 extern const struct iomap_ops btrfs_dio_iomap_ops;
diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index 88eb4c5ddd52..dd7fec85fea1 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -3,6 +3,7 @@
  * Copyright (C) 2007 Oracle.  All rights reserved.
  */
 
+#include <linux/encoded_io.h>
 #include <linux/fs.h>
 #include <linux/pagemap.h>
 #include <linux/time.h>
@@ -1993,6 +1994,32 @@ static ssize_t btrfs_direct_write(struct kiocb *iocb, 
struct iov_iter *from)
        return written ? written : err;
 }
 
+static ssize_t btrfs_encoded_write(struct kiocb *iocb, struct iov_iter *from)
+{
+       struct file *file = iocb->ki_filp;
+       struct inode *inode = file_inode(file);
+       struct encoded_iov encoded;
+       ssize_t ret;
+
+       ret = copy_encoded_iov_from_iter(&encoded, from);
+       if (ret)
+               return ret;
+
+       btrfs_inode_lock(inode, 0);
+       ret = generic_encoded_write_checks(iocb, &encoded);
+       if (ret || encoded.len == 0)
+               goto out;
+
+       ret = btrfs_write_check(iocb, from, encoded.len);
+       if (ret < 0)
+               goto out;
+
+       ret = btrfs_do_encoded_write(iocb, from, &encoded);
+out:
+       btrfs_inode_unlock(inode, 0);
+       return ret;
+}
+
 static ssize_t btrfs_file_write_iter(struct kiocb *iocb,
                                    struct iov_iter *from)
 {
@@ -2009,14 +2036,17 @@ static ssize_t btrfs_file_write_iter(struct kiocb *iocb,
        if (test_bit(BTRFS_FS_STATE_ERROR, &inode->root->fs_info->fs_state))
                return -EROFS;
 
-       if (!(iocb->ki_flags & IOCB_DIRECT) &&
-           (iocb->ki_flags & IOCB_NOWAIT))
+       if ((iocb->ki_flags & IOCB_NOWAIT) &&
+           (!(iocb->ki_flags & IOCB_DIRECT) ||
+            (iocb->ki_flags & IOCB_ENCODED)))
                return -EOPNOTSUPP;
 
        if (sync)
                atomic_inc(&inode->sync_writers);
 
-       if (iocb->ki_flags & IOCB_DIRECT)
+       if (iocb->ki_flags & IOCB_ENCODED)
+               num_written = btrfs_encoded_write(iocb, from);
+       else if (iocb->ki_flags & IOCB_DIRECT)
                num_written = btrfs_direct_write(iocb, from);
        else
                num_written = btrfs_buffered_write(iocb, from);
@@ -3587,7 +3617,7 @@ 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 | FMODE_BUF_RASYNC;
+       filp->f_mode |= FMODE_NOWAIT | FMODE_BUF_RASYNC | FMODE_ENCODED_IO;
        return generic_file_open(inode, filp);
 }
 
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 913f1eba3a92..c2fe76f57bf5 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -935,7 +935,7 @@ static noinline void submit_compressed_extents(struct 
async_chunk *async_chunk)
                                    ins.offset, async_extent->pages,
                                    async_extent->nr_pages,
                                    async_chunk->write_flags,
-                                   async_chunk->blkcg_css)) {
+                                   async_chunk->blkcg_css, true)) {
                        struct page *p = async_extent->pages[0];
                        const u64 start = async_extent->start;
                        const u64 end = start + async_extent->ram_size - 1;
@@ -2712,6 +2712,7 @@ static int insert_ordered_extent_file_extent(struct 
btrfs_trans_handle *trans,
         * except if the ordered extent was truncated.
         */
        update_inode_bytes = test_bit(BTRFS_ORDERED_DIRECT, &oe->flags) ||
+                            test_bit(BTRFS_ORDERED_ENCODED, &oe->flags) ||
                             test_bit(BTRFS_ORDERED_TRUNCATED, &oe->flags);
 
        return insert_reserved_file_extent(trans, BTRFS_I(oe->inode),
@@ -2746,7 +2747,8 @@ static int btrfs_finish_ordered_io(struct 
btrfs_ordered_extent *ordered_extent)
 
        if (!test_bit(BTRFS_ORDERED_NOCOW, &ordered_extent->flags) &&
            !test_bit(BTRFS_ORDERED_PREALLOC, &ordered_extent->flags) &&
-           !test_bit(BTRFS_ORDERED_DIRECT, &ordered_extent->flags))
+           !test_bit(BTRFS_ORDERED_DIRECT, &ordered_extent->flags) &&
+           !test_bit(BTRFS_ORDERED_ENCODED, &ordered_extent->flags))
                clear_bits |= EXTENT_DELALLOC_NEW;
 
        freespace_inode = btrfs_is_free_space_inode(inode);
@@ -10478,6 +10480,259 @@ ssize_t btrfs_encoded_read(struct kiocb *iocb, struct 
iov_iter *iter)
        return ret;
 }
 
+ssize_t btrfs_do_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 start, end;
+       u64 num_bytes, ram_bytes, disk_num_bytes;
+       unsigned long nr_pages, i;
+       struct page **pages;
+       struct btrfs_key ins;
+       bool extent_reserved = false;
+       struct extent_map *em;
+       ssize_t ret;
+
+       switch (encoded->compression) {
+       case ENCODED_IOV_COMPRESSION_BTRFS_ZLIB:
+               compression = BTRFS_COMPRESS_ZLIB;
+               break;
+       case ENCODED_IOV_COMPRESSION_BTRFS_ZSTD:
+               compression = BTRFS_COMPRESS_ZSTD;
+               break;
+       case ENCODED_IOV_COMPRESSION_BTRFS_LZO_4K:
+       case ENCODED_IOV_COMPRESSION_BTRFS_LZO_8K:
+       case ENCODED_IOV_COMPRESSION_BTRFS_LZO_16K:
+       case ENCODED_IOV_COMPRESSION_BTRFS_LZO_32K:
+       case ENCODED_IOV_COMPRESSION_BTRFS_LZO_64K:
+               /* The page size must match for LZO. */
+               if (encoded->compression -
+                   ENCODED_IOV_COMPRESSION_BTRFS_LZO_4K + 12 != PAGE_SHIFT)
+                       return -EINVAL;
+               compression = BTRFS_COMPRESS_LZO;
+               break;
+       default:
+               return -EINVAL;
+       }
+       if (encoded->encryption != ENCODED_IOV_ENCRYPTION_NONE)
+               return -EINVAL;
+
+       orig_count = iov_iter_count(from);
+
+       /* The extent size must be sane. */
+       if (encoded->unencoded_len > BTRFS_MAX_UNCOMPRESSED ||
+           orig_count > BTRFS_MAX_COMPRESSED || orig_count == 0)
+               return -EINVAL;
+
+       /*
+        * The compressed data must be smaller than the decompressed data.
+        *
+        * It's of course possible for data to compress to larger or the same
+        * size, but the buffered I/O path falls back to no compression for such
+        * data, and we don't want to break any assumptions by creating these
+        * extents.
+        *
+        * Note that this is less strict than the current check we have that the
+        * compressed data must be at least one sector smaller than the
+        * decompressed data. We only want to enforce the weaker requirement
+        * from old kernels that it is at least one byte smaller.
+        */
+       if (orig_count >= encoded->unencoded_len)
+               return -EINVAL;
+
+       /* The extent must start on a sector boundary. */
+       start = iocb->ki_pos;
+       if (!IS_ALIGNED(start, fs_info->sectorsize))
+               return -EINVAL;
+
+       /*
+        * The extent must end on a sector boundary. 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 unaligned end.
+        */
+       if (start + encoded->len < inode->i_size &&
+           !IS_ALIGNED(start + encoded->len, fs_info->sectorsize))
+               return -EINVAL;
+
+       /* Finally, the offset in the unencoded data must be sector-aligned. */
+       if (!IS_ALIGNED(encoded->unencoded_offset, fs_info->sectorsize))
+               return -EINVAL;
+
+       num_bytes = ALIGN(encoded->len, fs_info->sectorsize);
+       ram_bytes = ALIGN(encoded->unencoded_len, fs_info->sectorsize);
+       end = start + num_bytes - 1;
+
+       /*
+        * If the extent cannot be inline, the compressed data on disk must be
+        * sector-aligned. For convenience, we extend it with zeroes if it
+        * isn't.
+        */
+       disk_num_bytes = ALIGN(orig_count, fs_info->sectorsize);
+       nr_pages = DIV_ROUND_UP(disk_num_bytes, PAGE_SIZE);
+       pages = kvcalloc(nr_pages, sizeof(struct page *), GFP_KERNEL_ACCOUNT);
+       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_KERNEL_ACCOUNT | __GFP_HIGHMEM);
+               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, num_bytes);
+               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,
+                                                    num_bytes);
+               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();
+       }
+
+       /*
+        * We don't use the higher-level delalloc space functions because our
+        * num_bytes and disk_num_bytes are different.
+        */
+       ret = btrfs_alloc_data_chunk_ondemand(BTRFS_I(inode), disk_num_bytes);
+       if (ret)
+               goto out_unlock;
+       ret = btrfs_qgroup_reserve_data(BTRFS_I(inode), &data_reserved, start,
+                                       num_bytes);
+       if (ret)
+               goto out_free_data_space;
+       ret = btrfs_delalloc_reserve_metadata(BTRFS_I(inode), num_bytes,
+                                             disk_num_bytes);
+       if (ret)
+               goto out_qgroup_free_data;
+
+       /* Try an inline extent first. */
+       if (start == 0 && encoded->unencoded_len == encoded->len &&
+           encoded->unencoded_offset == 0) {
+               ret = cow_file_range_inline(BTRFS_I(inode), encoded->len,
+                                           orig_count, compression, pages,
+                                           true);
+               if (ret <= 0) {
+                       if (ret == 0)
+                               ret = orig_count;
+                       goto out_delalloc_release;
+               }
+       }
+
+       ret = btrfs_reserve_extent(root, disk_num_bytes, disk_num_bytes,
+                                  disk_num_bytes, 0, 0, &ins, 1, 1);
+       if (ret)
+               goto out_delalloc_release;
+       extent_reserved = true;
+
+       em = create_io_em(BTRFS_I(inode), start, num_bytes,
+                         start - encoded->unencoded_offset, ins.objectid,
+                         ins.offset, ins.offset, ram_bytes, compression,
+                         BTRFS_ORDERED_COMPRESSED);
+       if (IS_ERR(em)) {
+               ret = PTR_ERR(em);
+               goto out_free_reserved;
+       }
+       free_extent_map(em);
+
+       ret = btrfs_add_ordered_extent(BTRFS_I(inode), start, num_bytes,
+                                      ram_bytes, ins.objectid, ins.offset,
+                                      encoded->unencoded_offset,
+                                      (1 << BTRFS_ORDERED_ENCODED) |
+                                      (1 << BTRFS_ORDERED_COMPRESSED),
+                                      compression);
+       if (ret) {
+               btrfs_drop_extent_cache(BTRFS_I(inode), start, end, 0);
+               goto out_free_reserved;
+       }
+       btrfs_dec_block_group_reservations(fs_info, ins.objectid);
+
+       if (start + encoded->len > inode->i_size)
+               i_size_write(inode, start + encoded->len);
+
+       unlock_extent_cached(io_tree, start, end, &cached_state);
+
+       btrfs_delalloc_release_extents(BTRFS_I(inode), num_bytes);
+
+       if (btrfs_submit_compressed_write(BTRFS_I(inode), start, num_bytes,
+                                         ins.objectid, ins.offset, pages,
+                                         nr_pages, 0, NULL, 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;
+       }
+       ret = orig_count;
+       goto out;
+
+out_free_reserved:
+       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_extents(BTRFS_I(inode), num_bytes);
+       btrfs_delalloc_release_metadata(BTRFS_I(inode), disk_num_bytes,
+                                       ret < 0);
+out_qgroup_free_data:
+       if (ret < 0) {
+               btrfs_qgroup_free_data(BTRFS_I(inode), data_reserved, start,
+                                      num_bytes);
+       }
+out_free_data_space:
+       /*
+        * If btrfs_reserve_extent() succeeded, then we already decremented
+        * bytes_may_use.
+        */
+       if (!extent_reserved)
+               btrfs_free_reserved_data_space_noquota(fs_info, disk_num_bytes);
+out_unlock:
+       unlock_extent_cached(io_tree, start, end, &cached_state);
+out_pages:
+       for (i = 0; i < nr_pages; i++) {
+               if (pages[i])
+                       __free_page(pages[i]);
+       }
+       kvfree(pages);
+out:
+       if (ret >= 0)
+               iocb->ki_pos += encoded->len;
+       return ret;
+}
+
 #ifdef CONFIG_SWAP
 /*
  * Add an entry indicating a block group or device which is pinned by a
diff --git a/fs/btrfs/ordered-data.c b/fs/btrfs/ordered-data.c
index e11a517fab10..00329d82337e 100644
--- a/fs/btrfs/ordered-data.c
+++ b/fs/btrfs/ordered-data.c
@@ -472,9 +472,15 @@ void btrfs_remove_ordered_extent(struct btrfs_inode 
*btrfs_inode,
        spin_lock(&btrfs_inode->lock);
        btrfs_mod_outstanding_extents(btrfs_inode, -1);
        spin_unlock(&btrfs_inode->lock);
-       if (root != fs_info->tree_root)
-               btrfs_delalloc_release_metadata(btrfs_inode, entry->num_bytes,
-                                               false);
+       if (root != fs_info->tree_root) {
+               u64 release;
+
+               if (test_bit(BTRFS_ORDERED_ENCODED, &entry->flags))
+                       release = entry->disk_num_bytes;
+               else
+                       release = entry->num_bytes;
+               btrfs_delalloc_release_metadata(btrfs_inode, release, false);
+       }
 
        if (test_bit(BTRFS_ORDERED_DIRECT, &entry->flags))
                percpu_counter_add_batch(&fs_info->dio_bytes, -entry->num_bytes,
diff --git a/fs/btrfs/ordered-data.h b/fs/btrfs/ordered-data.h
index 8c8d6ed7a350..67c72485bd90 100644
--- a/fs/btrfs/ordered-data.h
+++ b/fs/btrfs/ordered-data.h
@@ -62,6 +62,8 @@ enum {
        BTRFS_ORDERED_LOGGED_CSUM,
        /* We wait for this extent to complete in the current transaction */
        BTRFS_ORDERED_PENDING,
+       /* RWF_ENCODED I/O */
+       BTRFS_ORDERED_ENCODED,
 };
 
 struct btrfs_ordered_extent {
-- 
2.30.2

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