* [REVIEW] Btrfs: Introduce ioctl for compressed size of file
2009-04-07 3:18 ` Chris Mason
@ 2009-04-19 3:56 ` Chris Ball
2009-04-23 19:20 ` Chris Mason
0 siblings, 1 reply; 4+ messages in thread
From: Chris Ball @ 2009-04-19 3:56 UTC (permalink / raw)
To: Chris Mason; +Cc: mp3geek, linux-btrfs
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 <cjb@laptop.org>
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