Bug 214719
| Summary: | ntfs3: disk usage of file not updated on overwrite by smaller file | ||
|---|---|---|---|
| Product: | File System | Reporter: | Ganapathi Kamath (hgkamath) |
| Component: | Other | Assignee: | fs_other |
| Status: | NEW --- | ||
| Severity: | normal | CC: | kari.argillander |
| Priority: | P1 | ||
| Hardware: | All | ||
| OS: | Linux | ||
| Kernel Version: | 5.15.0-0.rc3.20211001git4de593fb965f.30.fc35.x86_64 | Subsystem: | |
| Regression: | No | Bisected commit-id: | |
Emphasizing that this is with the NEW in-kernel paragon-NTFS3 driver and not the older fuseblk driver. I had to rpmbuild my own kernel using the fedora-rawhide srpm after enabling relevant kernel-configs setting for NTFS3. I could not find maintainer email-id in CC-field in bugzilla.kernel.org So I emailed MAINTAINERS NTFS3 FILESYSTEM M: Konstantin Komarov <almaz.alexandrovich@paragon-software.com> L: ntfs3@lists.linux.dev S: Supported W: http://www.paragon-software.com/ T: git https://github.com/Paragon-Software-Group/linux-ntfs3.git F: Documentation/filesystems/ntfs3.rst F: fs/ntfs3/ > Namjae Jeon: Can you check if below change fix your issue ? Sungjong find
> root cause and provide the change to me.
diff --git a/fs/exfat/inode.c b/fs/exfat/inode.c
index ca37d4344361..1c7aa1ea4724 100644
--- a/fs/exfat/inode.c
+++ b/fs/exfat/inode.c
@@ -604,7 +604,7 @@ static int exfat_fill_inode(struct inode *inode, struct exfat_dir_entry *info)
exfat_save_attr(inode, info->attr);
inode->i_blocks = ((i_size_read(inode) + (sbi->cluster_size - 1)) &
- ~(sbi->cluster_size - 1)) >> inode->i_blkbits;
+ ~((loff_t)sbi->cluster_size - 1)) >> inode->i_blkbits;
inode->i_mtime = info->mtime;
inode->i_ctime = info->mtime;
ei->i_crtime = info->crtime;
The issue of wrong disk-usage/allocated-block-size seems to be resolved.
Whether the block allocation is spec compliant/optimal is another issue/question.
which I can't comment as I don't know if right/wrong.
I have not read/dug into the ExFAT spec.
Below, in addition to logs, I have collected some extra troubleshooting.
In the qemu case I noted that there is a half-a-cluster of extra block-allocation.
See comments inline.
Btw, took me 3.5 hrs to build new kernel rpms. I installed, booted into kernel with the patch.
I neglected to keep their rpm-s of the older previous kernel-5.15.0-rc3 rpms prior to your patch, so I can't go back to the exact same custom-built-kernel without rebuilding. The next older kernel I have installed is fedora-34 5.14.9-300
[root@sirius gana]# mount /dev/sda16 /mnt/a16
[root@sirius gana]# rm /mnt/a16/test1.bin
rm: remove regular file '/mnt/a16/test1.bin'? y
[root@sirius gana]# umount /mnt/a16
[root@sirius gana]# mount /dev/sda16 /mnt/a16
[root@sirius gana]#
[root@sirius gana]# dd if=/dev/zero of=/mnt/a16/test1.bin bs=1M count=6000
6000+0 records in
6000+0 records out
6291456000 bytes (6.3 GB, 5.9 GiB) copied, 17.3153 s, 363 MB/s
[root@sirius gana]# ls -ls /mnt/a16/test1.bin
6144000 -rwxr-xr-x. 1 root root 6291456000 Oct 15 19:25 /mnt/a16/test1.bin
[root@sirius gana]# stat /mnt/a16/test1.bin
File: /mnt/a16/test1.bin
Size: 6291456000 Blocks: 12288000 IO Block: 131072 regular file
Device: 10300h/66304d Inode: 155 Links: 1
Access: (0755/-rwxr-xr-x) Uid: ( 0/ root) Gid: ( 0/ root)
Context: system_u:object_r:dosfs_t:s0
Access: 2021-10-15 19:25:30.000000000 +0530
Modify: 2021-10-15 19:25:48.800000000 +0530
Change: 2021-10-15 19:25:48.800000000 +0530
Birth: 2021-10-15 19:25:31.490000000 +0530
[root@sirius gana]#
[root@sirius gana]#
[root@sirius gana]# umount /mnt/a16
[root@sirius gana]# mount /dev/sda16 /mnt/a16
[root@sirius gana]#
[root@sirius gana]# ls -ls /mnt/a16/test1.bin
6144000 -rwxr-xr-x. 1 root root 6291456000 Oct 15 19:25 /mnt/a16/test1.bin
[root@sirius gana]# stat /mnt/a16/test1.bin
File: /mnt/a16/test1.bin
Size: 6291456000 Blocks: 12288000 IO Block: 131072 regular file
Device: 10300h/66304d Inode: 156 Links: 1
Access: (0755/-rwxr-xr-x) Uid: ( 0/ root) Gid: ( 0/ root)
Context: system_u:object_r:dosfs_t:s0
Access: 2021-10-15 19:25:30.000000000 +0530
Modify: 2021-10-15 19:25:48.800000000 +0530
Change: 2021-10-15 19:25:48.800000000 +0530
Birth: 2021-10-15 19:25:31.490000000 +0530
[root@sirius gana]#
[root@sirius gana]# echo $((6291456000/512)) 512 byte blocks = $((6291456000/1024)) kB
12288000 512 byte blocks = 6144000 kB
[root@sirius gana]# # seems like fixed ! Blocks count is preserved on unmount
[root@sirius gana]# # also note, that in this case allocation is perfect, no extra unused blocks.
[root@sirius gana]#
[root@sirius gana]# umount /mnt/a16
[root@sirius gana]# mount /dev/sda16 /mnt/a16
[root@sirius gana]# rm /mnt/a16/test1.bin
rm: remove regular file '/mnt/a16/test1.bin'? y
[root@sirius gana]# umount /mnt/a16
[root@sirius gana]# mount /dev/sda16 /mnt/a16
[root@sirius gana]# qemu-img create -f qcow2 /mnt/a16/test1.bin 6G
Formatting '/mnt/a16/test1.bin', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=6442450944 lazy_refcounts=off refcount_bits=16
[root@sirius gana]# ls -ls /mnt/a16/test1.bin
256 -rwxr-xr-x. 1 root root 196704 Oct 15 19:27 /mnt/a16/test1.bin
[root@sirius gana]# stat /mnt/a16/test1.bin
File: /mnt/a16/test1.bin
Size: 196704 Blocks: 512 IO Block: 131072 regular file
Device: 10300h/66304d Inode: 158 Links: 1
Access: (0755/-rwxr-xr-x) Uid: ( 0/ root) Gid: ( 0/ root)
Context: system_u:object_r:dosfs_t:s0
Access: 2021-10-15 19:27:56.000000000 +0530
Modify: 2021-10-15 19:27:57.990000000 +0530
Change: 2021-10-15 19:27:57.990000000 +0530
Birth: 2021-10-15 19:27:57.930000000 +0530
[root@sirius gana]# echo $((512*512)) " Bytes, " $((512*512-196704)) " Bytes extra"
262144 Bytes, 65440 Bytes extra
[root@sirius gana]# qemu-img create -f qcow2 -o preallocation=falloc /mnt/a16/test1.bin 6G
Formatting '/mnt/a16/test1.bin', fmt=qcow2 cluster_size=65536 extended_l2=off preallocation=falloc compression_type=zlib size=6442450944 lazy_refcounts=off refcount_bits=16
[root@sirius gana]# ls -ls /mnt/a16/test1.bin
6292736 -rwxr-xr-x. 1 root root 6443696128 Oct 15 19:28 /mnt/a16/test1.bin
[root@sirius gana]# stat /mnt/a16/test1.bin
File: /mnt/a16/test1.bin
Size: 6443696128 Blocks: 12585472 IO Block: 131072 regular file
Device: 10300h/66304d Inode: 158 Links: 1
Access: (0755/-rwxr-xr-x) Uid: ( 0/ root) Gid: ( 0/ root)
Context: system_u:object_r:dosfs_t:s0
Access: 2021-10-15 19:28:44.000000000 +0530
Modify: 2021-10-15 19:28:45.510000000 +0530
Change: 2021-10-15 19:28:45.510000000 +0530
Birth: 2021-10-15 19:27:57.930000000 +0530
[root@sirius gana]# echo $((12585472*512)) " Bytes, " $((12585472*512-6443696128)) " Bytes extra"
6443761664 Bytes, 65536 Bytes extra
[root@sirius gana]# echo $((6*1024*1024*1024))
6442450944
[root@sirius gana]# echo $((6443696128/131072))
49161
[root@sirius gana]# echo $((6443696128-49161*131072))
65536
[root@sirius gana]# # seems like 128 blocks are extra allocated for no reason.
[root@sirius gana]#
[root@sirius gana]#
[root@sirius gana]# umount /mnt/a16
[root@sirius gana]# mount /dev/sda16 /mnt/a16
[root@sirius gana]#
[root@sirius gana]# ls -ls /mnt/a16/test1.bin
6292736 -rwxr-xr-x. 1 root root 6443696128 Oct 15 19:28 /mnt/a16/test1.bin
[root@sirius gana]# stat /mnt/a16/test1.bin
File: /mnt/a16/test1.bin
Size: 6443696128 Blocks: 12585472 IO Block: 131072 regular file
Device: 10300h/66304d Inode: 159 Links: 1
Access: (0755/-rwxr-xr-x) Uid: ( 0/ root) Gid: ( 0/ root)
Context: system_u:object_r:dosfs_t:s0
Access: 2021-10-15 19:28:44.000000000 +0530
Modify: 2021-10-15 19:28:45.510000000 +0530
Change: 2021-10-15 19:28:45.510000000 +0530
Birth: 2021-10-15 19:27:57.930000000 +0530
[root@sirius gana]#
[root@sirius gana]# # well,
[root@sirius gana]# # (1) the allocated size greater than file-size, thats a good thing
[root@sirius gana]# # and (2) block count is preserved during unmount and remount
The below are extra troubleshoorting
[root@sirius gana]# dump.exfat /dev/sda16
exfatprogs version : 1.1.2
-------------- Dump Boot sector region --------------
Volume Length(sectors): 305061888
FAT Offset(sector offset): 2048
FAT Length(sectors): 9472
Cluster Heap Offset (sector offset): 12288
Cluster Count: 1191600
Root Cluster (cluster offset): 5
Volume Serial: 0xf13ff267
Sector Size Bits: 9
Sector per Cluster bits: 8
----------------- Dump Root entries -----------------
Volume entry type: 0x83
Volume label: CPERF0
Volume label character count: 6
Bitmap entry type: 0x81
Bitmap start cluster: 2
Bitmap size: 148950
Upcase table entry type: 0x82
Upcase table start cluster: 4
Upcase table size: 5836
---------------- Show the statistics ----------------
Cluster size: 131072
Total Clusters: 1191600
Free Clusters: 537402
The dump.exfat says exfat clustersize is 131072 (twice of 65536)
What happens on btrfs ? BTRFS does support sparse.
[root@sirius gana]# rm -f /opt/tmp/test*
[root@sirius gana]#
[root@sirius gana]# qemu-img create -f qcow2 /opt/tmp/test1.bin 6G
Formatting '/opt/tmp/test1.bin', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=6442450944 lazy_refcounts=off refcount_bits=16
[root@sirius gana]# ls -ls /opt/tmp/test1.bin
196 -rw-r--r--. 1 root root 196704 Oct 15 19:57 /opt/tmp/test1.bin
[root@sirius gana]# stat /opt/tmp/test1.bin
File: /opt/tmp/test1.bin
Size: 196704 Blocks: 392 IO Block: 4096 regular file
Device: 22h/34d Inode: 1844292 Links: 1
Access: (0644/-rw-r--r--) Uid: ( 0/ root) Gid: ( 0/ root)
Context: unconfined_u:object_r:usr_t:s0
Access: 2021-10-15 19:57:48.865554058 +0530
Modify: 2021-10-15 19:57:48.859554007 +0530
Change: 2021-10-15 19:57:48.859554007 +0530
Birth: 2021-10-15 19:57:48.836553809 +0530
[root@sirius gana]#
[root@sirius gana]# echo $((392*512)) " Bytes, " $((392*512-196704)) " Bytes extra"
200704 Bytes, 4000 Bytes extra
[root@sirius gana]#
[root@sirius gana]# qemu-img create -f qcow2 -o preallocation=falloc /opt/tmp/test1.bin 6G
Formatting '/opt/tmp/test1.bin', fmt=qcow2 cluster_size=65536 extended_l2=off preallocation=falloc compression_type=zlib size=6442450944 lazy_refcounts=off refcount_bits=16
[root@sirius gana]# ls -ls /opt/tmp/test1.bin
6292612 -rw-r--r--. 1 root root 6443696128 Oct 15 19:59 /opt/tmp/test1.bin
[root@sirius gana]# stat /opt/tmp/test1.bin
File: /opt/tmp/test1.bin
Size: 6443696128 Blocks: 12585224 IO Block: 4096 regular file
Device: 22h/34d Inode: 1844292 Links: 1
Access: (0644/-rw-r--r--) Uid: ( 0/ root) Gid: ( 0/ root)
Context: unconfined_u:object_r:usr_t:s0
Access: 2021-10-15 19:59:45.364560032 +0530
Modify: 2021-10-15 19:59:45.355559953 +0530
Change: 2021-10-15 19:59:45.355559953 +0530
Birth: 2021-10-15 19:57:48.836553809 +0530
[root@sirius gana]# echo $((12585224*512)) " Bytes, " $((12585224*512-6443696128)) " Bytes extra"
6443634688 Bytes, -61440 Bytes extra
[root@sirius gana]# find /opt/tmp -type f -printf "%S\t%p\n" | gawk '$1 <1.0 {print}'
0.99999 /opt/tmp/test1.bin
[root@sirius gana]#
[root@sirius gana]# qemu-img create -f qcow2 -o preallocation=full /opt/tmp/test1.bin 6G
Formatting '/opt/tmp/test1.bin', fmt=qcow2 cluster_size=65536 extended_l2=off preallocation=full compression_type=zlib size=6442450944 lazy_refcounts=off refcount_bits=16
[root@sirius gana]# ls -ls /opt/tmp/test1.bin
6292612 -rw-r--r--. 1 root root 6443696128 Oct 15 20:02 /opt/tmp/test1.bin
[root@sirius gana]# stat /opt/tmp/test1.bin
File: /opt/tmp/test1.bin
Size: 6443696128 Blocks: 12585224 IO Block: 4096 regular file
Device: 22h/34d Inode: 1844292 Links: 1
Access: (0644/-rw-r--r--) Uid: ( 0/ root) Gid: ( 0/ root)
Context: unconfined_u:object_r:usr_t:s0
Access: 2021-10-15 20:02:56.627193628 +0530
Modify: 2021-10-15 20:02:56.617193505 +0530
Change: 2021-10-15 20:02:56.617193505 +0530
Birth: 2021-10-15 19:57:48.836553809 +0530
[root@sirius gana]# echo $((12585224*512)) " Bytes, " $((12585224*512-6443696128)) " Bytes extra"
6443634688 Bytes, -61440 Bytes extra
[root@sirius gana]# find /opt/tmp -type f -printf "%S\t%p\n" | gawk '$1 <1.0 {print}'
0.99999 /opt/tmp/test1.bin
[root@sirius gana]#
[root@sirius gana]# # File size bigger than blocks allocated.
[root@sirius gana]# # Both prealloc schemes 'falloc' and 'full' seem to be a bit sparse.
[root@sirius gana]# # Which, is strange, as 'falloc' and 'full' preallocations are not meant to be sparse.
[root@sirius gana]# # But, this is btrfs.
What happens if 1 character is added to a large file on exfat?
[root@sirius gana]# rm /mnt/a16/test1.bin
rm: remove regular file '/mnt/a16/test1.bin'? y
[root@sirius gana]# dd if=/dev/zero of=/mnt/a16/test1.bin bs=1M count=6000
6000+0 records in
6000+0 records out
6291456000 bytes (6.3 GB, 5.9 GiB) copied, 11.1701 s, 563 MB/s
[root@sirius gana]# #printf "Q" >> /mnt/a16/test1.bin
[root@sirius gana]# ls -ls /mnt/a16/test1.bin
6144000 -rwxr-xr-x. 1 root root 6291456000 Oct 15 19:45 /mnt/a16/test1.bin
[root@sirius gana]# stat /mnt/a16/test1.bin
File: /mnt/a16/test1.bin
Size: 6291456000 Blocks: 12288000 IO Block: 131072 regular file
Device: 10300h/66304d Inode: 271 Links: 1
Access: (0755/-rwxr-xr-x) Uid: ( 0/ root) Gid: ( 0/ root)
Context: system_u:object_r:dosfs_t:s0
Access: 2021-10-15 19:45:12.000000000 +0530
Modify: 2021-10-15 19:45:23.320000000 +0530
Change: 2021-10-15 19:45:23.320000000 +0530
Birth: 2021-10-15 19:45:12.150000000 +0530
[root@sirius gana]# printf "Q" >> /mnt/a16/test1.bin
[root@sirius gana]# ls -ls /mnt/a16/test1.bin
6144128 -rwxr-xr-x. 1 root root 6291456001 Oct 15 19:46 /mnt/a16/test1.bin
[root@sirius gana]# stat /mnt/a16/test1.bin
File: /mnt/a16/test1.bin
Size: 6291456001 Blocks: 12288256 IO Block: 131072 regular file
Device: 10300h/66304d Inode: 271 Links: 1
Access: (0755/-rwxr-xr-x) Uid: ( 0/ root) Gid: ( 0/ root)
Context: system_u:object_r:dosfs_t:s0
Access: 2021-10-15 19:45:12.000000000 +0530
Modify: 2021-10-15 19:46:02.410000000 +0530
Change: 2021-10-15 19:46:02.410000000 +0530
Birth: 2021-10-15 19:45:12.150000000 +0530
root@sirius gana]#
root@sirius gana]# # adding 1 extra character allocates 128 blocks = 65536 bytes = half a cluster
Not that I am complaining. I don't know if this is correct or not.
Why is the allocation unit 65536 = 64 Kb = 128 blocks, when clustersize is 131072 = 128 Kb = 256 blocks?
The below link also says default cluster size is 128Kb for volume-sizes of 32 GB to 256 TB
https://support.microsoft.com/en-us/topic/default-cluster-size-for-ntfs-fat-and-exfat-9772e6f1-e31a-00d7-e18f-73169155af95
ouch sorry, ignore previous comment. Not for this bug, my mistake, sorry. This bug still exists. Status: RESOLVED FIXED https://lore.kernel.org/ntfs3/aaf41f35-b702-b391-1cff-de4688b3bb65@paragon-software.com/ |
[1.] One line summary of the problem: ntfs3: disk usage of file not updated when overwritten by smaller sized file [2.] Full description of the problem/report: disk usage is correct on first write. File overwrite only updates the disk-usage when the file is overwritten with larger file When a smaller file is copied onto existing file, previous disk usage is retained. This is not how btrfs works. When disk-usage of file is incorrect, it introduces confusion into disk-usage reporting tools like baobab, diskonaut, qdirstat etc. More info noted below. [3.] Keywords (i.e., modules, networking, kernel): ntfs3 [4.] Kernel information self built from 5.15.0-rc3 from fedora rawhide srpm [root@sirius gana]# uname -a Linux sirius 5.15.0-0.rc3.20211001git4de593fb965f.30.fc35.x86_64 #1 SMP Sun Oct3 23:12:17 IST 2021 x86_64 x86_64 x86_64 GNU/Linux [4.1.] Kernel version (from /proc/version): [root@sirius gana]# cat /proc/version Linux version 5.15.0-0.rc3.20211001git4de593fb965f.30.fc35.x86_64 (gana@sirius)(gcc (GCC) 11.2.1 20210728 (Red Hat 11.2.1-1), GNU ld version 2.37-10.fc35) #1 SMP Sun Oct 3 23:12:17 IST 2021 [4.2.] Kernel .config file: [root@sirius gana]# grep -Ei "exfat|ntfs" /boot/config-5.15.0-0.rc3.20211001git4de593fb965f.30.fc35.x86_64 # DOS/FAT/EXFAT/NT Filesystems CONFIG_EXFAT_FS=m CONFIG_EXFAT_DEFAULT_IOCHARSET="utf8" # CONFIG_NTFS_FS is not set CONFIG_NTFS3_FS=m # CONFIG_NTFS3_64BIT_CLUSTER is not set CONFIG_NTFS3_LZX_XPRESS=y # CONFIG_NTFS3_FS_POSIX_ACL is not set # end of DOS/FAT/EXFAT/NT Filesystems [5.] Most recent kernel version which did not have the bug: NA [6.] Output of Oops.. message (if applicable) with symbolic information resolved (see Documentation/admin-guide/bug-hunting.rst) NA [7.] A small shell script or example program which triggers the problem (if possible) [root@sirius gana]# ls -ls /mnt/a16/WinOS_j186nr_VB.vhdx 4096 -rwxr-xr-x. 1 root root 68723671040 Sep 16 16:46 /mnt/a16/WinOS_j186nr_VB.vhdx [8.] Environment [8.1.] Software (add the output of the ver_linux script here) [8.2.] Processor information (from /proc/cpuinfo): [root@sirius gana]# cat /proc/cpuinfo | grep "model name" | head -1 model name : Intel(R) Core(TM) i7-4700MQ CPU @ 2.40GHz [8.3.] Module information (from /proc/modules): [root@sirius gana]# cat /proc/modules | grep -Ei "exfat|ntfs" exfat 86016 2 - Live 0xffffffffc18e9000 ntfs3 266240 2 - Live 0xffffffffc11e3000 [8.4.] Loaded driver and hardware information (/proc/ioports, /proc/iomem) [8.5.] PCI information ('lspci -vvv' as root) [8.6.] SCSI information (from /proc/scsi/scsi) [8.7.] Other information that might be relevant to the problem (please look in /proc and include all information that you think to be relevant): [X.] Other notes, patches, fixes, workarounds: NA [2. cntd] This bug was encountered while attempting to reproduce #214701 and trying out many things. Doesn't seem to be related as in that bug it seems like an integer truncation problem. [root@sirius ~]# lsmod | grep -iE "ntfs3|exfat" exfat 86016 2 ntfs3 266240 3 [root@sirius ~]# cat /etc/mtab | grep -Ei "a16|a17" /dev/sda17 /mnt/a17 ntfs3 rw,relatime,nls=utf8 0 0 /dev/sda16 /mnt/a16 exfat rw,relatime,fmask=0022,dmask=0022,iocharset=utf8,errors=remount-ro 0 0 [root@sirius ~]# cat /proc/filesystems | grep -iE "ntfs3|exfat" ntfs3 exfat # a17 is the ntfs3 partition [root@sirius ~]# rm -f /mnt/a17/test1.bin /mnt/a17/test2.bin [root@sirius ~]# dd if=/dev/zero of=/mnt/a17/test1.bin bs=1M count=6000 6000+0 records in 6000+0 records out 6291456000 bytes (6.3 GB, 5.9 GiB) copied, 10.5367 s, 597 MB/s [root@sirius ~]# stat /mnt/a17/test1.bin File: /mnt/a17/test1.bin Size: 6291456000 Blocks: 12288000 IO Block: 4096 regular file Device: 10301h/66305d Inode: 48 Links: 1 Access: (0644/-rw-r--r--) Uid: ( 0/ root) Gid: ( 0/ root) Context: system_u:object_r:unlabeled_t:s0 Access: 2021-10-14 18:54:39.408368800 +0530 Modify: 2021-10-14 18:54:50.114470900 +0530 Change: 2021-10-14 18:54:50.114470900 +0530 Birth: 2021-10-14 18:54:39.408368800 +0530 [root@sirius ~]# dd if=/dev/zero of=/mnt/a17/test2.bin bs=1M count=3000 3000+0 records in 3000+0 records out 3145728000 bytes (3.1 GB, 2.9 GiB) copied, 4.8852 s, 644 MB/s [root@sirius ~]# ls -ls /mnt/a17/test1.bin /mnt/a17/test2.bin 6144000 -rw-r--r--. 1 root root 6291456000 Oct 14 18:47 /mnt/a17/test1.bin 3072000 -rw-r--r--. 1 root root 3145728000 Oct 14 18:47 /mnt/a17/test2.bin [root@sirius ~]# stat /mnt/a17/test2.bin File: /mnt/a17/test2.bin Size: 3145728000 Blocks: 6144000 IO Block: 4096 regular file Device: 10301h/66305d Inode: 47 Links: 1 Access: (0644/-rw-r--r--) Uid: ( 0/ root) Gid: ( 0/ root) Context: system_u:object_r:unlabeled_t:s0 Access: 2021-10-14 18:48:23.695787300 +0530 Modify: 2021-10-14 18:47:56.662529600 +0530 Change: 2021-10-14 18:47:56.662529600 +0530 Birth: 2021-10-14 18:47:51.778483100 +0530 [root@sirius ~]# cp /mnt/a17/test2.bin /mnt/a17/test1.bin cp: overwrite '/mnt/a17/test1.bin'? y [root@sirius ~]# ls -ls /mnt/a17/test1.bin /mnt/a17/test2.bin 6144000 -rw-r--r--. 1 root root 3145728000 Oct 14 18:48 /mnt/a17/test1.bin 3072000 -rw-r--r--. 1 root root 3145728000 Oct 14 18:47 /mnt/a17/test2.bin note that size (1k blocks used) field (1st column) is not updated. same happens with - using dd to overwrite the file - using "qemu-img create -f qcow2 -o preallocation=full /mnt/a16/test1.bin 6G" to overwrite the file as long as new file is of smaller size disk usage is not updated [root@sirius ~]# stat /mnt/a17/test1.bin File: /mnt/a17/test1.bin Size: 3145728000 Blocks: 12288000 IO Block: 4096 regular file Device: 10301h/66305d Inode: 46 Links: 1 Access: (0644/-rw-r--r--) Uid: ( 0/ root) Gid: ( 0/ root) Context: system_u:object_r:unlabeled_t:s0 Access: 2021-10-14 18:47:35.263325600 +0530 Modify: 2021-10-14 18:48:28.006828400 +0530 Change: 2021-10-14 18:48:28.006828400 +0530 Birth: 2021-10-14 18:47:35.263325600 +0530 In contrast, on btrfs, the expected happens [root@sirius ~]# dd if=/dev/zero of=/opt/tmp/test1.bin bs=1M count=6000 6000+0 records in 6000+0 records out 6291456000 bytes (6.3 GB, 5.9 GiB) copied, 9.78435 s, 643 MB/s [root@sirius ~]# dd if=/dev/zero of=/opt/tmp/test2.bin bs=1M count=3000 3000+0 records in 3000+0 records out 3145728000 bytes (3.1 GB, 2.9 GiB) copied, 3.91392 s, 804 MB/s [root@sirius ~]# ls -ls /opt/tmp/test1.bin /opt/tmp/test2.bin 6144000 -rw-r--r--. 1 root root 6291456000 Oct 14 18:35 /opt/tmp/test1.bin 3072000 -rw-r--r--. 1 root root 3145728000 Oct 14 18:36 /opt/tmp/test2.bin [root@sirius ~]# cp /opt/tmp/test2.bin /opt/tmp/test1.bin cp: overwrite '/opt/tmp/test1.bin'? y [root@sirius ~]# ls -ls /opt/tmp/test1.bin /opt/tmp/test2.bin 3072000 -rw-r--r--. 1 root root 3145728000 Oct 14 18:36 /opt/tmp/test1.bin 3072000 -rw-r--r--. 1 root root 3145728000 Oct 14 18:36 /opt/tmp/test2.bin Note that size (1k blocks used) field (1st column) is updated.