From: Rajeev Mishra <rajeevm@xxxxxxx>
In lo_calculate_size(), use vfs_getattr_nosec() for non-block files.
For block files, continue using i_size_read(). This improves size
accuracy on network and distributed filesystems.
Signed-off-by: Rajeev Mishra <rajeevm@xxxxxxx>
---
drivers/block/loop.c | 19 +++++++++++++++++--
1 file changed, 17 insertions(+), 2 deletions(-)
diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index 0e1b9eb9db10..a6214ae40ef0 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -139,9 +139,24 @@ static int part_shift;
static loff_t lo_calculate_size(struct loop_device *lo, struct file *file)
{
+ struct kstat stat;
loff_t loopsize;
- /* Compute loopsize in bytes */
- loopsize = i_size_read(file->f_mapping->host);
+ int ret;
+
+ /*
+ * Get the accurate file size. This provides better results than
+ * cached inode data, particularly for network filesystems where
+ * metadata may be stale.
+ */
+ if (S_ISBLK(file->f_inode->i_mode)) {
+ loopsize = i_size_read(file->f_mapping->host);
+ } else {
+ ret = vfs_getattr_nosec(&file->f_path, &stat, STATX_SIZE, 0);
+ if (ret)
+ return 0;
+ loopsize = stat.size;
+ }
+
if (lo->lo_offset > 0)
loopsize -= lo->lo_offset;
/* offset is beyond i_size, weird but possible */
--
2.47.3
