From mboxrd@z Thu Jan 1 00:00:00 1970 From: Chris Ball Subject: [REVIEW] Btrfs: Introduce ioctl for compressed size of file Date: Sat, 18 Apr 2009 23:56:11 -0400 Message-ID: References: <1239074313.17426.1.camel@think.oraclecorp.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: mp3geek , linux-btrfs@vger.kernel.org To: Chris Mason Return-path: In-Reply-To: <1239074313.17426.1.camel@think.oraclecorp.com> (Chris Mason's message of "Mon, 06 Apr 2009 23:18:33 -0400") List-ID: Hi, > We need to add an ioctl that reports on the actual size of the > compressed file. Here's an attempt at that ioctl, please review. The search code is based on the clone ioctl. Some specific questions: * Is the first while() loop necessary? * Are the semantics of returning -EINVAL when called on an FS with compression disabled desirable? Example usage: # ls -la english.txt -rw-r--r-- 1 root root 316601 2009-04-18 22:53 english.txt # python -c 'import fcntl; file = open("english.txt"); \ print fcntl.ioctl(file, 0x940f);' 151552 # gzip -1 english.txt; ls -la english.txt.gz -rw-r--r-- 1 root root 152737 2009-04-18 22:53 english.txt.gz Thanks, - Chris. --- fs/btrfs/ioctl.c | 113 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ fs/btrfs/ioctl.h | 1 + 2 files changed, 114 insertions(+), 0 deletions(-) diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c index bca729f..ae50c3b 100644 --- a/fs/btrfs/ioctl.c +++ b/fs/btrfs/ioctl.c @@ -1013,6 +1013,117 @@ out_drop_write: return ret; } +static unsigned long btrfs_ioctl_compsize(struct file *file) +{ + /* This ioctl returns the compressed size of an inode on disk + * by counting the on-disk space used by all of its extents. + */ + struct inode *inode = fdentry(file)->d_inode; + struct btrfs_root *root = BTRFS_I(inode)->root; + struct btrfs_path *path; + struct extent_buffer *leaf; + struct btrfs_key key; + u32 nritems; + int slot; + u64 olen = inode->i_size; + u64 len = olen; + unsigned long ret; + unsigned long compressed_size = 0; + + if (!btrfs_test_opt(root, COMPRESS)) + return -EINVAL; + + if (S_ISDIR(inode->i_mode)) + return -EISDIR; + + path = btrfs_alloc_path(); + if (!path) + return -ENOMEM; + + path->reada = 2; + mutex_lock(&inode->i_mutex); + + /* do any pending delalloc/csum calc on inode, one way or + another, and lock file content */ + while (1) { + struct btrfs_ordered_extent *ordered; + lock_extent(&BTRFS_I(inode)->io_tree, 0, len, GFP_NOFS); + ordered = btrfs_lookup_first_ordered_extent(inode, len); + if (BTRFS_I(inode)->delalloc_bytes == 0 && !ordered) + break; + unlock_extent(&BTRFS_I(inode)->io_tree, 0, len, GFP_NOFS); + if (ordered) + btrfs_put_ordered_extent(ordered); + btrfs_wait_ordered_range(inode, 0, len); + } + + /* search for the inode */ + key.objectid = inode->i_ino; + key.type = BTRFS_EXTENT_DATA_KEY; + key.offset = 0; + + while (1) { + /* note the key will change type as we walk through the tree */ + ret = btrfs_search_slot(NULL, root, &key, path, 0, 0); + if (ret < 0) + goto out; + + nritems = btrfs_header_nritems(path->nodes[0]); + if (path->slots[0] >= nritems) { + ret = btrfs_next_leaf(root, path); + if (ret < 0) + goto out; + if (ret > 0) + break; + nritems = btrfs_header_nritems(path->nodes[0]); + } + leaf = path->nodes[0]; + slot = path->slots[0]; + + btrfs_item_key_to_cpu(leaf, &key, slot); + if (btrfs_key_type(&key) > BTRFS_EXTENT_DATA_KEY || + key.objectid != inode->i_ino) + break; + + if (btrfs_key_type(&key) == BTRFS_EXTENT_DATA_KEY) { + struct btrfs_file_extent_item *extent; + int type; + u64 datal = 0; + + extent = btrfs_item_ptr(leaf, slot, + struct btrfs_file_extent_item); + type = btrfs_file_extent_type(leaf, extent); + if (type == BTRFS_FILE_EXTENT_REG) { + datal = btrfs_file_extent_num_bytes(leaf, + extent); + compressed_size += + btrfs_file_extent_disk_num_bytes(leaf, + extent); + } else if (type == BTRFS_FILE_EXTENT_INLINE) { + datal = btrfs_file_extent_ram_bytes(leaf, + extent); + compressed_size += + btrfs_file_extent_inline_item_len(leaf, + btrfs_item_nr(leaf, slot)); + } + btrfs_release_path(root, path); + } + + btrfs_release_path(root, path); + key.offset++; + } + + /* We've succeeded in going through all extents; set the final size. */ + ret = compressed_size; + +out: + btrfs_release_path(root, path); + unlock_extent(&BTRFS_I(inode)->io_tree, 0, len, GFP_NOFS); + mutex_unlock(&inode->i_mutex); + btrfs_free_path(path); + return ret; +} + static long btrfs_ioctl_clone_range(struct file *file, void __user *argp) { struct btrfs_ioctl_clone_range_args args; @@ -1122,6 +1233,8 @@ long btrfs_ioctl(struct file *file, unsigned int return btrfs_ioctl_trans_start(file); case BTRFS_IOC_TRANS_END: return btrfs_ioctl_trans_end(file); + case BTRFS_IOC_COMPR_SIZE: + return btrfs_ioctl_compsize(file); case BTRFS_IOC_SYNC: btrfs_sync_fs(file->f_dentry->d_sb, 1); return 0; diff --git a/fs/btrfs/ioctl.h b/fs/btrfs/ioctl.h index b320b10..bd2f866 100644 --- a/fs/btrfs/ioctl.h +++ b/fs/btrfs/ioctl.h @@ -66,4 +66,5 @@ struct btrfs_ioctl_clone_range_args { #define BTRFS_IOC_SUBVOL_CREATE _IOW(BTRFS_IOCTL_MAGIC, 14, \ struct btrfs_ioctl_vol_args) +#define BTRFS_IOC_COMPR_SIZE _IO(BTRFS_IOCTL_MAGIC, 15) #endif -- Chris Ball