Go through all extents of a file in a given [start,end) range and sum for: * regular extent: ->block_len, size is already rounded up to blocks * inline extents: length rounded up to 512
The range is start inclusive / end exclusive. For the whole file pass 0 and (u64)-1. The resulting value is number of occupied 512B sectors so this can be easily compared to stat.st_blocks to determine rough compression ratio of a file. Based on implementation from Ulrich Hecht, http://comments.gmane.org/gmane.comp.file-systems.btrfs/6253 Signed-off-by: David Sterba <dste...@suse.cz> --- fs/btrfs/ioctl.c | 77 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ fs/btrfs/ioctl.h | 11 +++++++ 2 files changed, 88 insertions(+), 0 deletions(-) diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c index c04f02c..82c3810 100644 --- a/fs/btrfs/ioctl.c +++ b/fs/btrfs/ioctl.c @@ -2972,6 +2972,81 @@ static int build_ino_list(u64 inum, u64 offset, u64 root, void *ctx) return 0; } +/* + * Returns the compressed size of an inode in 512 byte blocks. + * Count the on-disk space used by extents starting in range [start, end), + * inline data are rounded up to sector, ie. 512. + * + * The range is start inclusive and end exclusive so it can be used to + * determine compressed size of a given extent by its start and start of the + * next extent easily, without counting length. + * Whole file is specified as start = 0, end = (u64)-1 + */ +static long btrfs_ioctl_compr_size(struct file *file, void __user *argp) +{ + struct inode *inode = fdentry(file)->d_inode; + struct btrfs_ioctl_compr_size_args compr_args; + u64 len; + u64 compressed_size = 0; + u64 offset = 0; + + if (S_ISDIR(inode->i_mode)) + return -EISDIR; + + if (copy_from_user(&compr_args, argp, + sizeof(struct btrfs_ioctl_compr_size_args))) + return -EFAULT; + + if (compr_args.start > compr_args.end) + return -EINVAL; + + mutex_lock(&inode->i_mutex); + + offset = compr_args.start; + if (inode->i_size > compr_args.end) + len = compr_args.end; + else + len = inode->i_size; + + /* + * do any pending delalloc/csum calc on inode, one way or + * another, and lock file content + */ + btrfs_wait_ordered_range(inode, compr_args.start, len); + + while (offset < len) { + struct extent_map *em; + + em = btrfs_get_extent(inode, NULL, 0, offset, 1, 0); + if (IS_ERR_OR_NULL(em)) + goto error; + if (em->block_len != (u64)-1) + compressed_size += em->block_len; + else if (em->block_start == EXTENT_MAP_INLINE) { + compressed_size += ALIGN(em->len, 512); + } + offset += em->len; + free_extent_map(em); + } + mutex_unlock(&inode->i_mutex); + + unlock_extent(&BTRFS_I(inode)->io_tree, compr_args.start, len, GFP_NOFS); + + compr_args.size = compressed_size >> 9; + + if (copy_to_user(argp, &compr_args, sizeof(struct + btrfs_ioctl_compr_size_args))) + return -EFAULT; + + return 0; + +error: + mutex_unlock(&inode->i_mutex); + unlock_extent(&BTRFS_I(inode)->io_tree, compr_args.start, len, GFP_NOFS); + + return -EIO; +} + static long btrfs_ioctl_logical_to_ino(struct btrfs_root *root, void __user *arg) { @@ -3110,6 +3185,8 @@ long btrfs_ioctl(struct file *file, unsigned int return btrfs_ioctl_scrub_cancel(root, argp); case BTRFS_IOC_SCRUB_PROGRESS: return btrfs_ioctl_scrub_progress(root, argp); + case BTRFS_IOC_COMPR_SIZE: + return btrfs_ioctl_compr_size(file, argp); } return -ENOTTY; diff --git a/fs/btrfs/ioctl.h b/fs/btrfs/ioctl.h index 252ae99..bce761c 100644 --- a/fs/btrfs/ioctl.h +++ b/fs/btrfs/ioctl.h @@ -217,6 +217,15 @@ struct btrfs_ioctl_logical_ino_args { __u64 inodes; }; +struct btrfs_ioctl_compr_size_args { + /* Range start, inclusive */ + __u64 start; /* in */ + /* Range end, exclusive */ + __u64 end; /* in */ + __u64 size; /* out */ + __u64 reserved[2]; +}; + #define BTRFS_IOC_SNAP_CREATE _IOW(BTRFS_IOCTL_MAGIC, 1, \ struct btrfs_ioctl_vol_args) #define BTRFS_IOC_DEFRAG _IOW(BTRFS_IOCTL_MAGIC, 2, \ @@ -276,5 +285,7 @@ struct btrfs_ioctl_logical_ino_args { struct btrfs_ioctl_ino_path_args) #define BTRFS_IOC_LOGICAL_INO _IOWR(BTRFS_IOCTL_MAGIC, 36, \ struct btrfs_ioctl_ino_path_args) +#define BTRFS_IOC_COMPR_SIZE _IOR(BTRFS_IOCTL_MAGIC, 51, \ + struct btrfs_ioctl_compr_size_args) #endif -- 1.7.7.3 -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
