Returns a file's size on disk. Had been posted by Chris Ball over a year ago
(http://article.gmane.org/gmane.comp.file-systems.btrfs/2873). Chris Mason
suggested a couple of improvements back then, which I have implemented in
this version:
- use u64 to return the result
- replaced the loop
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);
}
with
btrfs_wait_ordered_range(inode, 0, (u64)-1);
- return the uncompressed size on disk for uncompressed filesystems instead
of EINVAL
Minimal example:
#include <sys/ioctl.h>
#include <fcntl.h>
#include <stdint.h>
#include <stdio.h>
#define BTRFS_IOCTL_MAGIC 0x94
#define BTRFS_IOC_COMPR_SIZE _IOR(BTRFS_IOCTL_MAGIC, 21, uint64_t)
int main(int argc, char **argv)
{
uint64_t size = -1;
int d = open(argv[1], O_RDONLY);
ioctl(d, BTRFS_IOC_COMPR_SIZE, &size);
printf("%zd\n", size);
return 0;
}
Signed-off-by: Ulrich Hecht <u...@suse.de>
---
fs/btrfs/ioctl.c | 103 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
fs/btrfs/ioctl.h | 1 +
2 files changed, 104 insertions(+), 0 deletions(-)
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 9254b3d..d18401b 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -1750,6 +1750,107 @@ out_drop_write:
return ret;
}
+static long btrfs_ioctl_compsize(struct file *file, void __user *argp)
+{
+ /* 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;
+ long ret;
+ u64 compressed_size = 0;
+
+ 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 */
+ btrfs_wait_ordered_range(inode, 0, (u64)-1);
+
+ /* 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. */
+ if (copy_to_user(argp, &compressed_size, sizeof(compressed_size)))
+ ret = -EFAULT;
+ else
+ ret = 0;
+
+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;
@@ -2034,6 +2135,8 @@ long btrfs_ioctl(struct file *file, unsigned int
case BTRFS_IOC_SYNC:
btrfs_sync_fs(file->f_dentry->d_sb, 1);
return 0;
+ case BTRFS_IOC_COMPR_SIZE:
+ return btrfs_ioctl_compsize(file, argp);
}
return -ENOTTY;
diff --git a/fs/btrfs/ioctl.h b/fs/btrfs/ioctl.h
index 424694a..a01ef1e 100644
--- a/fs/btrfs/ioctl.h
+++ b/fs/btrfs/ioctl.h
@@ -178,4 +178,5 @@ struct btrfs_ioctl_space_args {
#define BTRFS_IOC_DEFAULT_SUBVOL _IOW(BTRFS_IOCTL_MAGIC, 19, u64)
#define BTRFS_IOC_SPACE_INFO _IOWR(BTRFS_IOCTL_MAGIC, 20, \
struct btrfs_ioctl_space_args)
+#define BTRFS_IOC_COMPR_SIZE _IOR(BTRFS_IOCTL_MAGIC, 21, u64)
#endif
--
1.7.1
--
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