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 whole a file pass 0 and (u64)-1. The values returned are number of occupied 512B sectors for uncompressed and compressed size and can be easily compared to determine rough compression ratio of the given file range. Based on implementation from Ulrich Hecht, http://comments.gmane.org/gmane.comp.file-systems.btrfs/6253 Signed-off-by: David Sterba <dste...@suse.cz> --- V1-V2: * count uncompressed length as well * add missed lock_extent * properly ordered unlocking sequence of mutex and extent fs/btrfs/ioctl.c | 82 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ fs/btrfs/ioctl.h | 12 ++++++++ 2 files changed, 94 insertions(+), 0 deletions(-) diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c index c04f02c..4e058d7 100644 --- a/fs/btrfs/ioctl.c +++ b/fs/btrfs/ioctl.c @@ -2972,6 +2972,86 @@ 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 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); + + lock_extent(&BTRFS_I(inode)->io_tree, compr_args.start, len, GFP_NOFS); + + 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; + size += ALIGN(em->len, inode->i_sb->s_blocksize); + } else if (em->block_start == EXTENT_MAP_INLINE) { + compressed_size += ALIGN(em->len, 512); + size += ALIGN(em->len, 512); + } + offset += em->len; + free_extent_map(em); + } + unlock_extent(&BTRFS_I(inode)->io_tree, compr_args.start, len, GFP_NOFS); + mutex_unlock(&inode->i_mutex); + + compr_args.size = size >> 9; + compr_args.compressed_size = compressed_size >> 9; + + if (copy_to_user(argp, &compr_args, + sizeof(struct btrfs_ioctl_compr_size_args))) + return -EFAULT; + + return 0; + +error: + unlock_extent(&BTRFS_I(inode)->io_tree, compr_args.start, len, GFP_NOFS); + mutex_unlock(&inode->i_mutex); + + return -EIO; +} + static long btrfs_ioctl_logical_to_ino(struct btrfs_root *root, void __user *arg) { @@ -3110,6 +3190,8 @@ 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..d7b425a 100644 --- a/fs/btrfs/ioctl.h +++ b/fs/btrfs/ioctl.h @@ -217,6 +217,16 @@ 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 compressed_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 +286,7 @@ 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 -- 1.7.6.233.gd79bc -- 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
