Commit 47b71abd authored by Rajeev Mishra's avatar Rajeev Mishra Committed by Jens Axboe
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loop: use vfs_getattr_nosec for accurate file size 



Use vfs_getattr_nosec() in lo_calculate_size() for getting the file
size, rather than just read the cached inode size via i_size_read().
This provides better results than cached inode data, particularly for
network filesystems where metadata may be stale.

Signed-off-by: default avatarRajeev Mishra <rajeevm@hpe.com>
Reviewed-by: default avatarYu Kuai <yukuai3@huawei.com>
Link: https://lore.kernel.org/r/20250818184821.115033-3-rajeevm@hpe.com


[axboe: massage commit message]
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 8aa5a3b6

drivers/block/loop.c

+13 −2
Original line number Diff line number Diff line
@@ -139,9 +139,20 @@ 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.

	 */

	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 */