[LU-2935] layout swap on open unlinked file appears to succeed at first but does not

Tue, 15 Oct 2013 14:55:52 +0000

Layout swap in which one file is unlinked after open appears to succeed, but the data in the remaining file will be unreadable after cache invalidation.

fd0 = open("f0", O_RDWR|O_CREAT, 0666);
fd1 = open("f1", O_RDWR|O_CREAT, 0666);
unlink("f1");
swap_layouts(fd0, fd1);
close(fd0);
close(fd1);
umount
mount
fd0 = open("f0", O_RDWR|O_CREAT, 0666);
read(fd0, buf, size); returns -ENOENT.

# llmount.sh
# cd /mnt/lustre
# echo 000 > f0
# echo 111 > f1
# exec 7<>f1
# rm f1
# lfs swap_layouts f0 /proc/self/fd/7
# exec 7>&-
# cat f0
111
# cat f0
111
# cat f0
111
# cat f1
cat: f1: No such file or directory
# cat f0
cat: f0: No such file or directory
# ls
f0
# stat f0
  File: `f0'
  Size: 4         	Blocks: 8          IO Block: 4194304 regular file
Device: 2c54f966h/743766374d	Inode: 144115205255725073  Links: 1
Access: (0644/-rw-r--r--)  Uid: (    0/    root)   Gid: (    0/    root)
Access: 2013-03-08 14:32:29.000000000 -0600
Modify: 2013-03-08 14:32:29.000000000 -0600
Change: 2013-03-08 14:32:29.000000000 -0600
# cat f0
cat: f0: No such file or directory
# strace cat f0
execve("/bin/cat", ["cat", "f0"], [/* 36 vars */]) = 0
...
open("f0", O_RDONLY)                    = 3
fstat(3, {st_mode=S_IFREG|0644, st_size=4, ...}) = 0
...
read(3, 0x7f4ef153f000, 4194304)        = -1 ENOENT (No such file or directory)
...

Whamcloud Community JIRA

[LU-2935] layout swap on open unlinked file appears to succeed at first but does not