* [PATCH v4 1/2] loop: Consolidate size calculation logic into lo_calculate_size()
2025-08-18 18:48 fixed commit message Rajeev Mishra
@ 2025-08-18 18:48 ` Rajeev Mishra
2025-08-18 18:48 ` [PATCH v4 2/2] loop: use vfs_getattr_nosec for accurate file size Rajeev Mishra
` (2 subsequent siblings)
3 siblings, 0 replies; 5+ messages in thread
From: Rajeev Mishra @ 2025-08-18 18:48 UTC (permalink / raw)
To: axboe, yukuai1; +Cc: linux-block, linux-kernel, Rajeev Mishra
Renamed get_size to lo_calculate_size and merged the logic from
get_size and get_loop_size into a single function.
Updated all callers to use lo_calculate_size
Signed-off-by: Rajeev Mishra <rajeevm@hpe.com>
---
drivers/block/loop.c | 26 +++++++++-----------------
1 file changed, 9 insertions(+), 17 deletions(-)
diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index 1b6ee91f8eb9..0e1b9eb9db10 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -137,20 +137,18 @@ static void loop_global_unlock(struct loop_device *lo, bool global)
static int max_part;
static int part_shift;
-static loff_t get_size(loff_t offset, loff_t sizelimit, struct file *file)
+static loff_t lo_calculate_size(struct loop_device *lo, struct file *file)
{
loff_t loopsize;
-
/* Compute loopsize in bytes */
loopsize = i_size_read(file->f_mapping->host);
- if (offset > 0)
- loopsize -= offset;
+ if (lo->lo_offset > 0)
+ loopsize -= lo->lo_offset;
/* offset is beyond i_size, weird but possible */
if (loopsize < 0)
return 0;
-
- if (sizelimit > 0 && sizelimit < loopsize)
- loopsize = sizelimit;
+ if (lo->lo_sizelimit > 0 && lo->lo_sizelimit < loopsize)
+ loopsize = lo->lo_sizelimit;
/*
* Unfortunately, if we want to do I/O on the device,
* the number of 512-byte sectors has to fit into a sector_t.
@@ -158,11 +156,6 @@ static loff_t get_size(loff_t offset, loff_t sizelimit, struct file *file)
return loopsize >> 9;
}
-static loff_t get_loop_size(struct loop_device *lo, struct file *file)
-{
- return get_size(lo->lo_offset, lo->lo_sizelimit, file);
-}
-
/*
* We support direct I/O only if lo_offset is aligned with the logical I/O size
* of backing device, and the logical block size of loop is bigger than that of
@@ -569,7 +562,7 @@ static int loop_change_fd(struct loop_device *lo, struct block_device *bdev,
error = -EINVAL;
/* size of the new backing store needs to be the same */
- if (get_loop_size(lo, file) != get_loop_size(lo, old_file))
+ if (lo_calculate_size(lo, file) != lo_calculate_size(lo, old_file))
goto out_err;
/*
@@ -1063,7 +1056,7 @@ static int loop_configure(struct loop_device *lo, blk_mode_t mode,
loop_update_dio(lo);
loop_sysfs_init(lo);
- size = get_loop_size(lo, file);
+ size = lo_calculate_size(lo, file);
loop_set_size(lo, size);
/* Order wrt reading lo_state in loop_validate_file(). */
@@ -1255,8 +1248,7 @@ loop_set_status(struct loop_device *lo, const struct loop_info64 *info)
if (partscan)
clear_bit(GD_SUPPRESS_PART_SCAN, &lo->lo_disk->state);
if (!err && size_changed) {
- loff_t new_size = get_size(lo->lo_offset, lo->lo_sizelimit,
- lo->lo_backing_file);
+ loff_t new_size = lo_calculate_size(lo, lo->lo_backing_file);
loop_set_size(lo, new_size);
}
out_unlock:
@@ -1399,7 +1391,7 @@ static int loop_set_capacity(struct loop_device *lo)
if (unlikely(lo->lo_state != Lo_bound))
return -ENXIO;
- size = get_loop_size(lo, lo->lo_backing_file);
+ size = lo_calculate_size(lo, lo->lo_backing_file);
loop_set_size(lo, size);
return 0;
--
2.43.7
^ permalink raw reply [flat|nested] 5+ messages in thread* [PATCH v4 2/2] loop: use vfs_getattr_nosec for accurate file size
2025-08-18 18:48 fixed commit message Rajeev Mishra
2025-08-18 18:48 ` [PATCH v4 1/2] loop: Consolidate size calculation logic into lo_calculate_size() Rajeev Mishra
@ 2025-08-18 18:48 ` Rajeev Mishra
2025-08-18 19:07 ` fixed commit message Jens Axboe
2025-08-18 19:10 ` Jens Axboe
3 siblings, 0 replies; 5+ messages in thread
From: Rajeev Mishra @ 2025-08-18 18:48 UTC (permalink / raw)
To: axboe, yukuai1; +Cc: linux-block, linux-kernel, Rajeev Mishra
In lo_calculate_size, use vfs_getattr_nosec() instead of
i_size_read(), which improves accuracy for network and
distributed filesystems.
Signed-off-by: Rajeev Mishra <rajeevm@hpe.com>
---
drivers/block/loop.c | 15 +++++++++++++--
1 file changed, 13 insertions(+), 2 deletions(-)
diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index 0e1b9eb9db10..57263c273f0f 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -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 */
--
2.43.7
^ permalink raw reply [flat|nested] 5+ messages in thread