Ceph » CephFS

PR to enable overwriting till actually file-size: https://github.com/ceph/ceph/pull/46267

Tested with ceph-fuse client:
1. create on the mount-point FILE > 64k

-rw-rw-r--. 1 tshacked tshacked 65547 May 15 11:28 FILE

2. set max_file_size to 64k (min val)

3. Code_with_PR: overwrite data works fine w/o returning "File too large" error

$ printf "11111111111"| dd of=FILE bs=512 seek=128 conv=notrunc
0+1 records in
0+1 records out
11 bytes copied, 0.0467811 s, 0.2 kB/s

4. request to overwrite which exceeded file-size returned error even though data is being overwrites (with or w/o PR)

$ printf "222222222222"| dd of=FILE bs=512 seek=128 conv=notrunc
dd: error writing 'FILE': File too large
0+1 records in
0+0 records out
0 bytes copied, 0.000336058 s, 0.0 kB/s

The behavior in (4) seems to be ambiguous - the fop fails while the data is partially updated (till file-size).
Should the data be updated error is returned?
I"ll check if posix define it and what happen on local FS

On F34 (FS XFS) attempt to overwrite from file-size-limit fails w/o any write.
This is not the case on the upstream which returns error but also do the overwrite

#-rw-r--r--. 1 root root 65553 May 16 15:06 FILE
# set -o posix
# ulimit -f 128   # limit file-size to 64k
# printf "XXXX" | dd of=FILE bs=512 seek=128 conv=notrunc
File size limit exceeded (core dumped)

During the work I saw a 2nd issue which I didn't fix and exists on the upstream code:
1. ceph_max_file = default
2. create file-size=64k+10b

$ ll /mnt/ceph/FILE 
-rw-rw-r--. 1 tshacked tshacked 65546 May 23 19:28 /mnt/ceph/FILE

$ hexdump -c -s 65530 /mnt/ceph/FILE
000fffa  \t 023   W   O 277   I   1   2   3   4   5   6   7   8   9  \n
001000a

3. limit ceph_max_file = 64k
4. write 20b at offset 64k
5. result: EFBIG and data is written till actual size.

$ printf "TAMAR12345TAMAR6789" | dd of=/mnt/ceph/FILE bs=512 seek=128 conv=notrunc
dd: error writing '/mnt/ceph/FILE': File too large
0+1 records in
0+0 records out
0 bytes copied, 0.00121106 s, 0.0 kB/s
$ ll /mnt/ceph/FILE 
-rw-rw-r--. 1 tshacked tshacked 65546 May 23 19:28 /mnt/ceph/FILE

$ hexdump -c -s 65530 /mnt/ceph/FILE
000fffa  \t 023   W   O 277   I   T   A   M   A   R   1   2   3   4   5
001000a