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@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; +}