[PATCH v11 08/14] btrfs: add BTRFS_IOC_ENCODED_READ

Omar Sandoval
2021-09-01T17:01:43Z

From: Omar Sandoval <osandov@fb.com>

There are 4 main cases:

1. Inline extents: we copy the data straight out of the extent buffer.
2. Hole/preallocated extents: we fill in zeroes.
3. Regular, uncompressed extents: we read the sectors we need directly
from disk.
4. Regular, compressed extents: we read the entire compressed extent
from disk and indicate what subset of the decompressed extent is in
the file.

This initial implementation simplifies a few things that can be improved
in the future:

- We hold the inode lock during the operation.
- Cases 1, 3, and 4 allocate temporary memory to read into before
copying out to userspace.
- We don't do read repair, because it turns out that read repair is
currently broken for compressed data.

Signed-off-by: Omar Sandoval <osandov@fb.com>
---
fs/btrfs/ctree.h | 4 +
fs/btrfs/inode.c | 489 +++++++++++++++++++++++++++++++++++++++++++++++
fs/btrfs/ioctl.c | 111 +++++++++++
3 files changed, 604 insertions(+)

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index b95ec5fb68d5..cbd7e07c1c34 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -3223,6 +3223,10 @@ int btrfs_writepage_cow_fixup(struct page *page);
void btrfs_writepage_endio_finish_ordered(struct btrfs_inode *inode,
struct page *page, u64 start,
u64 end, bool uptodate);
+struct btrfs_ioctl_encoded_io_args;
+ssize_t btrfs_encoded_read(struct kiocb *iocb, struct iov_iter *iter,
+ struct btrfs_ioctl_encoded_io_args *encoded);
+
extern const struct dentry_operations btrfs_dentry_operations;
extern const struct iomap_ops btrfs_dio_iomap_ops;
extern const struct iomap_dio_ops btrfs_dio_ops;
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index a87a34f56234..1940f22179ba 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -10500,6 +10500,495 @@ void btrfs_set_range_writeback(struct btrfs_inode *inode, u64 start, u64 end)
}
}

+static int btrfs_encoded_io_compression_from_extent(int compress_type)
+{
+ switch (compress_type) {
+ case BTRFS_COMPRESS_NONE:
+ return BTRFS_ENCODED_IO_COMPRESSION_NONE;
+ case BTRFS_COMPRESS_ZLIB:
+ return BTRFS_ENCODED_IO_COMPRESSION_ZLIB;
+ case BTRFS_COMPRESS_LZO:
+ /*
+ * The LZO format depends on the page size. 64k is the maximum
+ * sectorsize (and thus page size) that we support.
+ */
+ if (PAGE_SIZE < SZ_4K || PAGE_SIZE > SZ_64K)
+ return -EINVAL;
+ return BTRFS_ENCODED_IO_COMPRESSION_LZO_4K + (PAGE_SHIFT - 12);
+ case BTRFS_COMPRESS_ZSTD:
+ return BTRFS_ENCODED_IO_COMPRESSION_ZSTD;
+ default:
+ return -EUCLEAN;
+ }
+}
+
+static ssize_t btrfs_encoded_read_inline(
+ struct kiocb *iocb,
+ struct iov_iter *iter, u64 start,
+ u64 lockend,
+ struct extent_state **cached_state,
+ u64 extent_start, size_t count,
+ struct btrfs_ioctl_encoded_io_args *encoded,
+ bool *unlocked)
+{
+ struct inode *inode = file_inode(iocb->ki_filp);
+ struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
+ struct btrfs_path *path;
+ struct extent_buffer *leaf;
+ struct btrfs_file_extent_item *item;
+ u64 ram_bytes;
+ unsigned long ptr;
+ void *tmp;
+ ssize_t ret;
+
+ path = btrfs_alloc_path();
+ if (!path) {
+ ret = -ENOMEM;
+ goto out;
+ }
+ ret = btrfs_lookup_file_extent(NULL, BTRFS_I(inode)->root, path,
+ btrfs_ino(BTRFS_I(inode)), extent_start,
+ 0);
+ if (ret) {
+ if (ret > 0) {
+ /* The extent item disappeared? */
+ ret = -EIO;
+ }
+ goto out;
+ }
+ leaf = path->nodes[0];
+ item = btrfs_item_ptr(leaf, path->slots[0],
+ struct btrfs_file_extent_item);
+
+ ram_bytes = btrfs_file_extent_ram_bytes(leaf, item);
+ ptr = btrfs_file_extent_inline_start(item);
+
+ encoded->len = (min_t(u64, extent_start + ram_bytes, inode->i_size) -
+ iocb->ki_pos);
+ ret = btrfs_encoded_io_compression_from_extent(
+ btrfs_file_extent_compression(leaf, item));
+ if (ret < 0)
+ goto out;
+ encoded->compression = ret;
+ if (encoded->compression) {
+ size_t inline_size;
+
+ inline_size = btrfs_file_extent_inline_item_len(leaf,
+ btrfs_item_nr(path->slots[0]));
+ if (inline_size > count) {
+ ret = -ENOBUFS;
+ goto out;
+ }
+ count = inline_size;
+ encoded->unencoded_len = ram_bytes;
+ encoded->unencoded_offset = iocb->ki_pos - extent_start;
+ } else {
+ encoded->len = encoded->unencoded_len = count =
+ min_t(u64, count, encoded->len);
+ ptr += iocb->ki_pos - extent_start;
+ }
+
+ tmp = kmalloc(count, GFP_NOFS);
+ if (!tmp) {
+ ret = -ENOMEM;
+ goto out;
+ }
+ read_extent_buffer(leaf, tmp, ptr, count);
+ btrfs_release_path(path);
+ unlock_extent_cached(io_tree, start, lockend, cached_state);
+ inode_unlock_shared(inode);
+ *unlocked = true;
+
+ ret = copy_to_iter(tmp, count, iter);
+ if (ret != count)
+ ret = -EFAULT;
+ kfree(tmp);
+out:
+ btrfs_free_path(path);
+ return ret;
+}
+
+struct btrfs_encoded_read_private {
+ struct inode *inode;
+ wait_queue_head_t wait;
+ atomic_t pending;
+ blk_status_t status;
+ bool skip_csum;
+};
+
+static blk_status_t submit_encoded_read_bio(struct inode *inode,
+ struct bio *bio, int mirror_num,
+ unsigned long bio_flags)
+{
+ struct btrfs_encoded_read_private *priv = bio->bi_private;
+ struct btrfs_io_bio *io_bio = btrfs_io_bio(bio);
+ struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
+ blk_status_t ret;
+
+ if (!priv->skip_csum) {
+ ret = btrfs_lookup_bio_sums(inode, bio, NULL);
+ if (ret)
+ return ret;
+ }
+
+ ret = btrfs_bio_wq_end_io(fs_info, bio, BTRFS_WQ_ENDIO_DATA);
+ if (ret) {
+ btrfs_io_bio_free_csum(io_bio);
+ return ret;
+ }
+
+ atomic_inc(&priv->pending);
+ ret = btrfs_map_bio(fs_info, bio, mirror_num);
+ if (ret) {
+ atomic_dec(&priv->pending);
+ btrfs_io_bio_free_csum(io_bio);
+ }
+ return ret;
+}
+
+static blk_status_t btrfs_encoded_read_check_bio(struct btrfs_io_bio *io_bio)
+{
+ const bool uptodate = io_bio->bio.bi_status == BLK_STS_OK;
+ struct btrfs_encoded_read_private *priv = io_bio->bio.bi_private;
+ struct inode *inode = priv->inode;
+ struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
+ u32 sectorsize = fs_info->sectorsize;
+ struct bio_vec *bvec;
+ struct bvec_iter_all iter_all;
+ u64 start = io_bio->logical;
+ u32 bio_offset = 0;
+
+ if (priv->skip_csum || !uptodate)
+ return io_bio->bio.bi_status;
+
+ bio_for_each_segment_all(bvec, &io_bio->bio, iter_all) {
+ unsigned int i, nr_sectors, pgoff;
+
+ nr_sectors = BTRFS_BYTES_TO_BLKS(fs_info, bvec->bv_len);
+ pgoff = bvec->bv_offset;
+ for (i = 0; i < nr_sectors; i++) {
+ ASSERT(pgoff < PAGE_SIZE);
+ if (check_data_csum(inode, io_bio, bio_offset,
+ bvec->bv_page, pgoff, start))
+ return BLK_STS_IOERR;
+ start += sectorsize;
+ bio_offset += sectorsize;
+ pgoff += sectorsize;
+ }
+ }
+ return BLK_STS_OK;
+}
+
+static void btrfs_encoded_read_endio(struct bio *bio)
+{
+ struct btrfs_encoded_read_private *priv = bio->bi_private;
+ struct btrfs_io_bio *io_bio = btrfs_io_bio(bio);
+ blk_status_t status;
+
+ status = btrfs_encoded_read_check_bio(io_bio);
+ if (status) {
+ /*
+ * The memory barrier implied by the atomic_dec_return() here
+ * pairs with the memory barrier implied by the
+ * atomic_dec_return() or io_wait_event() in
+ * btrfs_encoded_read_regular_fill_pages() to ensure that this
+ * write is observed before the load of status in
+ * btrfs_encoded_read_regular_fill_pages().
+ */
+ WRITE_ONCE(priv->status, status);
+ }
+ if (!atomic_dec_return(&priv->pending))
+ wake_up(&priv->wait);
+ btrfs_io_bio_free_csum(io_bio);
+ bio_put(bio);
+}
+
+static int btrfs_encoded_read_regular_fill_pages(struct inode *inode, u64 offset,
+ u64 disk_io_size, struct page **pages)
+{
+ struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
+ struct btrfs_encoded_read_private priv = {
+ .inode = inode,
+ .pending = ATOMIC_INIT(1),
+ .skip_csum = BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM,
+ };
+ unsigned long i = 0;
+ u64 cur = 0;
+ int ret;
+
+ init_waitqueue_head(&priv.wait);
+ /*
+ * Submit bios for the extent, splitting due to bio or stripe limits as
+ * necessary.
+ */
+ while (cur < disk_io_size) {
+ struct extent_map *em;
+ struct btrfs_io_geometry geom;
+ struct bio *bio = NULL;
+ u64 remaining;
+
+ em = btrfs_get_chunk_map(fs_info, offset + cur,
+ disk_io_size - cur);
+ if (IS_ERR(em)) {
+ ret = PTR_ERR(em);
+ } else {
+ ret = btrfs_get_io_geometry(fs_info, em, BTRFS_MAP_READ,
+ offset + cur, &geom);
+ free_extent_map(em);
+ }
+ if (ret) {
+ WRITE_ONCE(priv.status, errno_to_blk_status(ret));
+ break;
+ }
+ remaining = min(geom.len, disk_io_size - cur);
+ while (bio || remaining) {
+ size_t bytes = min_t(u64, remaining, PAGE_SIZE);
+
+ if (!bio) {
+ bio = btrfs_bio_alloc(offset + cur);
+ bio->bi_end_io = btrfs_encoded_read_endio;
+ bio->bi_private = &priv;
+ bio->bi_opf = REQ_OP_READ;
+ }
+
+ if (!bytes ||
+ bio_add_page(bio, pages[i], bytes, 0) < bytes) {
+ blk_status_t status;
+
+ status = submit_encoded_read_bio(inode, bio, 0,
+ 0);
+ if (status) {
+ WRITE_ONCE(priv.status, status);
+ bio_put(bio);
+ goto out;
+ }
+ bio = NULL;
+ continue;
+ }
+
+ i++;
+ cur += bytes;
+ remaining -= bytes;
+ }
+ }
+
+out:
+ if (atomic_dec_return(&priv.pending))
+ io_wait_event(priv.wait, !atomic_read(&priv.pending));
+ /* See btrfs_encoded_read_endio() for ordering. */
+ return blk_status_to_errno(READ_ONCE(priv.status));
+}
+
+static ssize_t btrfs_encoded_read_regular(struct kiocb *iocb,
+ struct iov_iter *iter,
+ u64 start, u64 lockend,
+ struct extent_state **cached_state,
+ u64 offset, u64 disk_io_size,
+ size_t count, bool compressed,
+ bool *unlocked)
+{
+ struct inode *inode = file_inode(iocb->ki_filp);
+ struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
+ struct page **pages;
+ unsigned long nr_pages, i;
+ u64 cur;
+ size_t page_offset;
+ ssize_t ret;
+
+ nr_pages = DIV_ROUND_UP(disk_io_size, PAGE_SIZE);
+ pages = kcalloc(nr_pages, sizeof(struct page *), GFP_NOFS);
+ if (!pages)
+ return -ENOMEM;
+ for (i = 0; i < nr_pages; i++) {
+ pages[i] = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
+ if (!pages[i]) {
+ ret = -ENOMEM;
+ goto out;
+ }
+ }
+
+ ret = btrfs_encoded_read_regular_fill_pages(inode, offset, disk_io_size,
+ pages);
+ if (ret)
+ goto out;
+
+ unlock_extent_cached(io_tree, start, lockend, cached_state);
+ inode_unlock_shared(inode);
+ *unlocked = true;
+
+ if (compressed) {
+ i = 0;
+ page_offset = 0;
+ } else {
+ i = (iocb->ki_pos - start) >> PAGE_SHIFT;
+ page_offset = (iocb->ki_pos - start) & (PAGE_SIZE - 1);
+ }
+ cur = 0;
+ while (cur < count) {
+ size_t bytes = min_t(size_t, count - cur,
+ PAGE_SIZE - page_offset);
+
+ if (copy_page_to_iter(pages[i], page_offset, bytes,
+ iter) != bytes) {
+ ret = -EFAULT;
+ goto out;
+ }
+ i++;
+ cur += bytes;
+ page_offset = 0;
+ }
+ ret = count;
+out:
+ for (i = 0; i < nr_pages; i++) {
+ if (pages[i])
+ __free_page(pages[i]);
+ }
+ kfree(pages);
+ return ret;
+}
+
+ssize_t btrfs_encoded_read(struct kiocb *iocb, struct iov_iter *iter,
+ struct btrfs_ioctl_encoded_io_args *encoded)
+{
+ struct inode *inode = file_inode(iocb->ki_filp);
+ struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
+ struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
+ ssize_t ret;
+ size_t count = iov_iter_count(iter);
+ u64 start, lockend, offset, disk_io_size;
+ struct extent_state *cached_state = NULL;
+ struct extent_map *em;
+ bool unlocked = false;
+
+ file_accessed(iocb->ki_filp);
+
+ inode_lock_shared(inode);
+
+ if (iocb->ki_pos >= inode->i_size) {
+ inode_unlock_shared(inode);
+ return 0;
+ }
+ start = ALIGN_DOWN(iocb->ki_pos, fs_info->sectorsize);
+ /*
+ * We don't know how long the extent containing iocb->ki_pos is, but if
+ * it's compressed we know that it won't be longer than this.
+ */
+ lockend = start + BTRFS_MAX_UNCOMPRESSED - 1;
+
+ for (;;) {
+ struct btrfs_ordered_extent *ordered;
+
+ ret = btrfs_wait_ordered_range(inode, start,
+ lockend - start + 1);
+ if (ret)
+ goto out_unlock_inode;
+ lock_extent_bits(io_tree, start, lockend, &cached_state);
+ ordered = btrfs_lookup_ordered_range(BTRFS_I(inode), start,
+ lockend - start + 1);
+ if (!ordered)
+ break;
+ btrfs_put_ordered_extent(ordered);
+ unlock_extent_cached(io_tree, start, lockend, &cached_state);
+ cond_resched();
+ }
+
+ em = btrfs_get_extent(BTRFS_I(inode), NULL, 0, start,
+ lockend - start + 1);
+ if (IS_ERR(em)) {
+ ret = PTR_ERR(em);
+ goto out_unlock_extent;
+ }
+
+ if (em->block_start == EXTENT_MAP_INLINE) {
+ u64 extent_start = em->start;
+
+ /*
+ * For inline extents we get everything we need out of the
+ * extent item.
+ */
+ free_extent_map(em);
+ em = NULL;
+ ret = btrfs_encoded_read_inline(iocb, iter, start, lockend,
+ &cached_state, extent_start,
+ count, encoded, &unlocked);
+ goto out;
+ }
+
+ /*
+ * We only want to return up to EOF even if the extent extends beyond
+ * that.
+ */
+ encoded->len = (min_t(u64, extent_map_end(em), inode->i_size) -
+ iocb->ki_pos);
+ if (em->block_start == EXTENT_MAP_HOLE ||
+ test_bit(EXTENT_FLAG_PREALLOC, &em->flags)) {
+ offset = EXTENT_MAP_HOLE;
+ encoded->len = encoded->unencoded_len = count =
+ min_t(u64, count, encoded->len);
+ } else if (test_bit(EXTENT_FLAG_COMPRESSED, &em->flags)) {
+ offset = em->block_start;
+ /*
+ * Bail if the buffer isn't large enough to return the whole
+ * compressed extent.
+ */
+ if (em->block_len > count) {
+ ret = -ENOBUFS;
+ goto out_em;
+ }
+ disk_io_size = count = em->block_len;
+ encoded->unencoded_len = em->ram_bytes;
+ encoded->unencoded_offset = iocb->ki_pos - em->orig_start;
+ ret = btrfs_encoded_io_compression_from_extent(
+ em->compress_type);
+ if (ret < 0)
+ goto out_em;
+ encoded->compression = ret;
+ } else {
+ offset = em->block_start + (start - em->start);
+ if (encoded->len > count)
+ encoded->len = count;
+ /*
+ * Don't read beyond what we locked. This also limits the page
+ * allocations that we'll do.
+ */
+ disk_io_size = min(lockend + 1,
+ iocb->ki_pos + encoded->len) - start;
+ encoded->len = encoded->unencoded_len = count =
+ start + disk_io_size - iocb->ki_pos;
+ disk_io_size = ALIGN(disk_io_size, fs_info->sectorsize);
+ }
+ free_extent_map(em);
+ em = NULL;
+
+ if (offset == EXTENT_MAP_HOLE) {
+ unlock_extent_cached(io_tree, start, lockend, &cached_state);
+ inode_unlock_shared(inode);
+ unlocked = true;
+ ret = iov_iter_zero(count, iter);
+ if (ret != count)
+ ret = -EFAULT;
+ } else {
+ ret = btrfs_encoded_read_regular(iocb, iter, start, lockend,
+ &cached_state, offset,
+ disk_io_size, count,
+ encoded->compression,
+ &unlocked);
+ }
+
+out:
+ if (ret >= 0)
+ iocb->ki_pos += encoded->len;
+out_em:
+ free_extent_map(em);
+out_unlock_extent:
+ if (!unlocked)
+ unlock_extent_cached(io_tree, start, lockend, &cached_state);
+out_unlock_inode:
+ if (!unlocked)
+ inode_unlock_shared(inode);
+ return ret;
+}
+
#ifdef CONFIG_SWAP
/*
* Add an entry indicating a block group or device which is pinned by a
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index fecb8bac11dd..4e619a10f236 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -28,6 +28,7 @@
#include <linux/iversion.h>
#include <linux/fileattr.h>
#include <linux/fsverity.h>
+#include <linux/sched/xacct.h>
#include "ctree.h"
#include "disk-io.h"
#include "export.h"
@@ -87,6 +88,22 @@ struct btrfs_ioctl_send_args_32 {

#define BTRFS_IOC_SEND_32 _IOW(BTRFS_IOCTL_MAGIC, 38, \
struct btrfs_ioctl_send_args_32)
+
+struct btrfs_ioctl_encoded_io_args_32 {
+ compat_uptr_t iov;
+ compat_ulong_t iovcnt;
+ __s64 offset;
+ __u64 flags;
+ __u64 len;
+ __u64 unencoded_len;
+ __u64 unencoded_offset;
+ __u32 compression;
+ __u32 encryption;
+ __u32 reserved[8];
+};
+
+#define BTRFS_IOC_ENCODED_READ_32 _IOR(BTRFS_IOCTL_MAGIC, 64, \
+ struct btrfs_ioctl_encoded_io_args_32)
#endif

/* Mask out flags that are inappropriate for the given type of inode. */
@@ -4824,6 +4841,94 @@ static int _btrfs_ioctl_send(struct file *file, void __user *argp, bool compat)
return ret;
}

+static int btrfs_ioctl_encoded_read(struct file *file, void __user *argp,
+ bool compat)
+{
+ struct btrfs_ioctl_encoded_io_args args;
+ size_t copy_end_kernel = offsetofend(struct btrfs_ioctl_encoded_io_args,
+ flags);
+ size_t copy_end;
+ struct iovec iovstack[UIO_FASTIOV];
+ struct iovec *iov = iovstack;
+ struct iov_iter iter;
+ loff_t pos;
+ struct kiocb kiocb;
+ ssize_t ret;
+
+ if (!capable(CAP_SYS_ADMIN)) {
+ ret = -EPERM;
+ goto out_acct;
+ }
+
+ if (compat) {
+#if defined(CONFIG_64BIT) && defined(CONFIG_COMPAT)
+ struct btrfs_ioctl_encoded_io_args_32 args32;
+
+ copy_end = offsetofend(struct btrfs_ioctl_encoded_io_args_32,
+ flags);
+ if (copy_from_user(&args32, argp, copy_end)) {
+ ret = -EFAULT;
+ goto out_acct;
+ }
+ args.iov = compat_ptr(args32.iov);
+ args.iovcnt = args32.iovcnt;
+ args.offset = args32.offset;
+ args.flags = args32.flags;
+#else
+ return -ENOTTY;
+#endif
+ } else {
+ copy_end = copy_end_kernel;
+ if (copy_from_user(&args, argp, copy_end)) {
+ ret = -EFAULT;
+ goto out_acct;
+ }
+ }
+ if (args.flags != 0) {
+ ret = -EINVAL;
+ goto out_acct;
+ }
+ memset((char *)&args + copy_end_kernel, 0,
+ sizeof(args) - copy_end_kernel);
+
+ ret = import_iovec(READ, args.iov, args.iovcnt, ARRAY_SIZE(iovstack),
+ &iov, &iter);
+ if (ret < 0)
+ goto out_acct;
+
+ if (iov_iter_count(&iter) == 0) {
+ ret = 0;
+ goto out_iov;
+ }
+ pos = args.offset;
+ ret = rw_verify_area(READ, file, &pos, args.len);
+ if (ret < 0)
+ goto out_iov;
+
+ init_sync_kiocb(&kiocb, file);
+ ret = kiocb_set_rw_flags(&kiocb, 0);
+ if (ret)
+ goto out_iov;
+ kiocb.ki_pos = pos;
+
+ ret = btrfs_encoded_read(&kiocb, &iter, &args);
+ if (ret >= 0) {
+ fsnotify_access(file);
+ if (copy_to_user(argp + copy_end,
+ (char *)&args + copy_end_kernel,
+ sizeof(args) - copy_end_kernel))
+ ret = -EFAULT;
+ }
+
+out_iov:
+ kfree(iov);
+out_acct:
+ if (ret > 0)
+ add_rchar(current, ret);
+ inc_syscr(current);
+ return ret;
+}
+
long btrfs_ioctl(struct file *file, unsigned int
cmd, unsigned long arg)
{
@@ -4968,6 +5073,12 @@ long btrfs_ioctl(struct file *file, unsigned int
return fsverity_ioctl_enable(file, (const void __user *)argp);
case FS_IOC_MEASURE_VERITY:
return fsverity_ioctl_measure(file, argp);
+ case BTRFS_IOC_ENCODED_READ:
+ return btrfs_ioctl_encoded_read(file, argp, false);
+#if defined(CONFIG_64BIT) && defined(CONFIG_COMPAT)
+ case BTRFS_IOC_ENCODED_READ_32:
+ return btrfs_ioctl_encoded_read(file, argp, true);
+#endif
}

return -ENOTTY;
--
2.33.0