On 12/19/2011 10:17 PM, David Sterba wrote: > 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 <dsterba@xxxxxxx> > --- > 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); > + missing a lock_extent() ? and we may adjust i_mutex and [un]lock_extent. thanks, liubo > + 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 -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
