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loop: use vfs_getattr_nosec for accurate file size

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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: Rajeev Mishra <rajeevm@hpe.com>
Reviewed-by: Yu Kuai <yukuai3@huawei.com>
Link: https://lore.kernel.org/r/20250818184821.115033-3-rajeevm@hpe.com
[axboe: massage commit message]
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Rajeev Mishra 2025-08-18 18:48:21 +00:00 committed by Jens Axboe
parent 8aa5a3b68a
commit 47b71abd58
1 changed files with 13 additions and 2 deletions
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15
drivers/block/loop.c
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@ -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 */