[PATCH U-BOOT 22/26] fs: btrfs: Introduce btrfs_read_extent_inline() and btrfs_read_extent_reg()

Qu Wenruo
2020-04-22T06:50:05Z

These two functions are used to do sector aligned read, which will be
later used to implement btrfs_file_read().

Signed-off-by: Qu Wenruo <wqu@suse.com>
---
fs/btrfs/ctree.h | 5 ++
fs/btrfs/disk-io.c | 36 ++++++++++
fs/btrfs/disk-io.h | 2 +
fs/btrfs/inode.c | 162 +++++++++++++++++++++++++++++++++++++++++++++
4 files changed, 205 insertions(+)

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index fe6966e896a1..602f99b5e593 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -1293,6 +1293,11 @@ int btrfs_iter_dir(struct btrfs_root *root, u64 ino,
int btrfs_lookup_path(struct btrfs_root *root, u64 ino, const char *filename,
struct btrfs_root **root_ret, u64 *ino_ret,
u8 *type_ret, int symlink_limit);
+int btrfs_read_extent_inline(struct btrfs_path *path,
+ struct btrfs_file_extent_item *fi, char *dest);
+int btrfs_read_extent_reg(struct btrfs_path *path,
+ struct btrfs_file_extent_item *fi, u64 offset,
+ int len, char *dest);

/* ctree.c */
int btrfs_comp_cpu_keys(const struct btrfs_key *k1, const struct btrfs_key *k2);
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 8dc816f7a8c9..be2c26d323f6 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -565,6 +565,42 @@ struct extent_buffer* read_tree_block(struct btrfs_fs_info *fs_info, u64 bytenr,
return ERR_PTR(ret);
}

+int read_extent_data(struct btrfs_fs_info *fs_info, char *data, u64 logical,
+ u64 *len, int mirror)
+{
+ u64 offset = 0;
+ struct btrfs_multi_bio *multi = NULL;
+ struct btrfs_device *device;
+ int ret = 0;
+ u64 max_len = *len;
+
+ ret = btrfs_map_block(fs_info, READ, logical, len, &multi, mirror,
+ NULL);
+ if (ret) {
+ fprintf(stderr, "Couldn't map the block %llu\n",
+ logical + offset);
+ goto err;
+ }
+ device = multi->stripes[0].dev;
+
+ if (*len > max_len)
+ *len = max_len;
+ if (!device->desc || !device->part) {
+ ret = -EIO;
+ goto err;
+ }
+
+ ret = __btrfs_devread(device->desc, device->part, data, *len,
+ multi->stripes[0].physical);
+ if (ret != *len)
+ ret = -EIO;
+ else
+ ret = 0;
+err:
+ kfree(multi);
+ return ret;
+}
+
void btrfs_setup_root(struct btrfs_root *root, struct btrfs_fs_info *fs_info,
u64 objectid)
{
diff --git a/fs/btrfs/disk-io.h b/fs/btrfs/disk-io.h
index d8f6f827550a..7c321d842561 100644
--- a/fs/btrfs/disk-io.h
+++ b/fs/btrfs/disk-io.h
@@ -18,6 +18,8 @@ int read_whole_eb(struct btrfs_fs_info *info, struct extent_buffer *eb, int mirr
struct extent_buffer* read_tree_block(struct btrfs_fs_info *fs_info, u64 bytenr,
u64 parent_transid);

+int read_extent_data(struct btrfs_fs_info *fs_info, char *data, u64 logical,
+ u64 *len, int mirror);
struct extent_buffer* btrfs_find_create_tree_block(
struct btrfs_fs_info *fs_info, u64 bytenr);
struct extent_buffer *btrfs_find_tree_block(struct btrfs_fs_info *fs_info,
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 797063449ca6..986b9347b012 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -5,9 +5,12 @@
* 2017 Marek Behun, CZ.NIC, marek.behun at nic.cz
*/

+#include <linux/kernel.h>
#include <malloc.h>
+#include <memalign.h>
#include "btrfs.h"
#include "disk-io.h"
+#include "volumes.h"

u64 __btrfs_lookup_inode_ref(struct __btrfs_root *root, u64 inr,
struct btrfs_inode_ref *refp, char *name)
@@ -652,3 +655,162 @@ out:
__btrfs_free_path(&path);
return rd_all;
}
+
+/*
+ * Read out inline extent.
+ *
+ * Since inline extent should only exist for offset 0, no need for extra
+ * parameters.
+ * Truncating should be handled by the caller.
+ *
+ * Return the number of bytes read.
+ * Return <0 for error.
+ */
+int btrfs_read_extent_inline(struct btrfs_path *path,
+ struct btrfs_file_extent_item *fi, char *dest)
+{
+ struct extent_buffer *leaf = path->nodes[0];
+ int slot = path->slots[0];
+ char *cbuf = NULL;
+ char *dbuf = NULL;
+ u32 csize;
+ u32 dsize;
+ int ret;
+
+ csize = btrfs_file_extent_inline_item_len(leaf, btrfs_item_nr(slot));
+ if (btrfs_file_extent_compression(leaf, fi) == BTRFS_COMPRESS_NONE) {
+ /* Uncompressed, just read it out */
+ read_extent_buffer(leaf, dest,
+ btrfs_file_extent_inline_start(fi),
+ csize);
+ return csize;
+ }
+
+ /* Compressed extent, prepare the compressed and data buffer */
+ dsize = btrfs_file_extent_ram_bytes(leaf, fi);
+ cbuf = malloc(csize);
+ dbuf = malloc(dsize);
+ if (!cbuf || !dbuf) {
+ ret = -ENOMEM;
+ goto out;
+ }
+ read_extent_buffer(leaf, cbuf, btrfs_file_extent_inline_start(fi),
+ csize);
+ ret = btrfs_decompress(btrfs_file_extent_compression(leaf, fi),
+ cbuf, csize, dbuf, dsize);
+ if (ret < 0 || ret != dsize) {
+ ret = -EIO;
+ goto out;
+ }
+ memcpy(dest, dbuf, dsize);
+ ret = dsize;
+out:
+ free(cbuf);
+ free(dbuf);
+ return ret;
+}
+
+/*
+ * Read out regular extent.
+ *
+ * Truncating should be handled by the caller.
+ *
+ * @offset and @len should not cross the extent boundary.
+ * Return the number of bytes read.
+ * Return <0 for error.
+ */
+int btrfs_read_extent_reg(struct btrfs_path *path,
+ struct btrfs_file_extent_item *fi, u64 offset,
+ int len, char *dest)
+{
+ struct extent_buffer *leaf = path->nodes[0];
+ struct btrfs_fs_info *fs_info = leaf->fs_info;
+ struct btrfs_key key;
+ u64 extent_num_bytes;
+ u64 disk_bytenr;
+ u64 read;
+ char *cbuf = NULL;
+ char *dbuf = NULL;
+ u32 csize;
+ u32 dsize;
+ bool finished = false;
+ int num_copies;
+ int i;
+ int slot = path->slots[0];
+ int ret;
+
+ btrfs_item_key_to_cpu(leaf, &key, slot);
+ extent_num_bytes = btrfs_file_extent_num_bytes(leaf, fi);
+ ASSERT(IS_ALIGNED(offset, fs_info->sectorsize) &&
+ IS_ALIGNED(len, fs_info->sectorsize));
+ ASSERT(offset >= key.offset &&
+ offset + len <= key.offset + extent_num_bytes);
+
+ /* Preallocated or hole , fill @dest with zero */
+ if (btrfs_file_extent_type(leaf, fi) == BTRFS_FILE_EXTENT_PREALLOC ||
+ btrfs_file_extent_disk_bytenr(leaf, fi) == 0) {
+ memset(dest, 0, len);
+ return len;
+ }
+
+ if (btrfs_file_extent_compression(leaf, fi) == BTRFS_COMPRESS_NONE) {
+ u64 logical;
+
+ logical = btrfs_file_extent_disk_bytenr(leaf, fi) +
+ btrfs_file_extent_offset(leaf, fi) +
+ offset - key.offset;
+ read = len;
+
+ num_copies = btrfs_num_copies(fs_info, logical, len);
+ for (i = 1; i <= num_copies; i++) {
+ ret = read_extent_data(fs_info, dest, logical, &read, i);
+ if (ret < 0 || read != len)
+ continue;
+ finished = true;
+ break;
+ }
+ if (!finished)
+ return -EIO;
+ return len;
+ }
+
+ csize = btrfs_file_extent_disk_num_bytes(leaf, fi);
+ dsize = btrfs_file_extent_ram_bytes(leaf, fi);
+ disk_bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
+ num_copies = btrfs_num_copies(fs_info, disk_bytenr, csize);
+
+ cbuf = malloc_cache_aligned(csize);
+ dbuf = malloc_cache_aligned(dsize);
+ if (!cbuf || !dbuf) {
+ ret = -ENOMEM;
+ goto out;
+ }
+ /* For compressed extent, we must read the whole on-disk extent */
+ for (i = 1; i <= num_copies; i++) {
+ read = csize;
+ ret = read_extent_data(fs_info, cbuf, disk_bytenr,
+ &read, i);
+ if (ret < 0 || read != csize)
+ continue;
+ finished = true;
+ break;
+ }
+ if (!finished) {
+ ret = -EIO;
+ goto out;
+ }
+
+ ret = btrfs_decompress(btrfs_file_extent_compression(leaf, fi), cbuf,
+ csize, dbuf, dsize);
+ if (ret != dsize) {
+ ret = -EIO;
+ goto out;
+ }
+ /* Then copy the needed part */
+ memcpy(dest, dbuf + btrfs_file_extent_offset(leaf, fi), len);
+ ret = len;
+out:
+ free(cbuf);
+ free(dbuf);
+ return ret;
+}
--
2.26.0