From: Goldwyn Rodrigues <rgoldwyn@xxxxxxxx>
btrfs_file_to_device_offset() converts a file offset to device offset.
It also calculates the last_index which represents the last page in the
range which is within the extent.
btrfs_file_to_device_offset() is only passed conditionally based on if
BTRFS_SHAREDEXT is set in the mount flag.
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@xxxxxxxx>
---
fs/btrfs/file.c | 42 ++++++++++++++++++++++++++++++++++++++++--
1 file changed, 40 insertions(+), 2 deletions(-)
diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index e171d822a05e..f0b97d020575 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -3643,18 +3643,56 @@ static ssize_t btrfs_direct_read(struct kiocb *iocb, struct iov_iter *to)
return ret;
}
+static pgoff_t btrfs_file_offset_to_device(struct file *filp, loff_t pos,
+ size_t len, pgoff_t *last_index)
+{
+ struct extent_map *em;
+ struct btrfs_inode *inode = BTRFS_I(file_inode(filp));
+ u64 device_offset;
+ u64 device_len;
+
+ if (inode->flags & BTRFS_INODE_NODATACOW)
+ return 0;
+
+ em = btrfs_get_extent(inode, NULL, 0, pos, len);
+
+ device_offset = em->block_start;
+ if (device_offset == EXTENT_MAP_HOLE) {
+ free_extent_map(em);
+ return 0;
+ }
+
+ /* Delalloc should be in file's pagecache */
+ BUG_ON(device_offset == EXTENT_MAP_DELALLOC);
+
+ device_offset = (device_offset + (pos - em->start)) >> PAGE_SHIFT;
+ device_len = (em->len - (pos - em->start)) >> PAGE_SHIFT;
+ *last_index = device_offset + device_len;
+
+ free_extent_map(em);
+
+ return device_offset;
+}
+
static ssize_t btrfs_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
{
ssize_t ret = 0;
+ struct inode *inode = file_inode(iocb->ki_filp);
+ struct btrfs_fs_info *fs_info;
+ file_offset_to_device_t file_offset_to_device = NULL;
if (iocb->ki_flags & IOCB_DIRECT) {
ret = btrfs_direct_read(iocb, to);
if (ret < 0 || !iov_iter_count(to) ||
- iocb->ki_pos >= i_size_read(file_inode(iocb->ki_filp)))
+ iocb->ki_pos >= i_size_read(inode))
return ret;
}
- return filemap_read(iocb, to, ret, NULL);
+ fs_info = btrfs_sb(inode->i_sb);
+ if (btrfs_test_opt(fs_info, SHAREDEXT))
+ file_offset_to_device = btrfs_file_offset_to_device;
+
+ return filemap_read(iocb, to, ret, file_offset_to_device);
}
const struct file_operations btrfs_file_operations = {
--
2.33.1
