getdents, unlink and tmpfs vs otherFS

getdents, unlink and tmpfs vs otherFS

[Michael Tokarev]

I've got a weird problem a while back - my initrd script
does not work when the root is on cciss device.  It turned
out to be a problem with $SUBJ.  /dev/cciss/ is quite large
(alot of disks and partitions), and when initrd is on tmpfs
(initramfs it really is), and run-init is executed, it tries
to remove /dev/cciss, it fails.  And here's why.

uclibc does the following on readdir():

open(.., O_DIRECTORY)                   = 3
getdents(3, /* 197 entries */, 3933)    = 3932
lseek(3, 2728, SEEK_SET)                = 2728
unlink(..)
....
getdents(3, /* 85 entries */, 3933)     = 1700
unlink()
....
getdents(3, /* 196 entries */, 3933)    = 3920
lseek(3, 6816, SEEK_SET)                = 6816
....

and finally rmdir() which fails with "Directory
not empty" error.

And eg glibc, or dietlibc, or klibc - it's all
the same but without all the lseek()s, and with
final rmdir() successeful.

It's on tmpfs.

On ext[23], final rmdir succed on both cases,
ie, with and without lseek.

Is it a bug in tmpfs, or in uclibc?

Thanks.

/mjt