Hi there, I noticed two little misfeatures in the hostfs file system. The first one is most certainly a bug, the second one might be functioning as intended.
1. If a file is held read-only by one process it cannot by creat()'ed by another one: [EMAIL PROTECTED] ~]# mount -t hostfs none /mnt [EMAIL PROTECTED] ~]# cd /mnt/tmp [EMAIL PROTECTED] tmp]# touch foo [EMAIL PROTECTED] tmp]# tail -f foo & [1] 895 [EMAIL PROTECTED] tmp]# > foo -bash: foo: Invalid argument [EMAIL PROTECTED] tmp]# kill 895 [1]+ Terminated tail -f foo [EMAIL PROTECTED] tmp]# > foo I tracked that problem down to the set_attr() function in hostfs_user.c: It tries to ftruncate() the read-only file descriptor. The file should be re-opened writable before changing its length. 2. As long as a file is held open changes made outside the UML kernel (i.e. on the host side) may not be visible: [EMAIL PROTECTED] tmp]# tail -f foo & [1] 897 # Host system: echo "Hello World" > /tmp/foo [EMAIL PROTECTED] tmp]# cat foo [EMAIL PROTECTED] tmp]# kill 897 [1]+ Terminated tail -f foo [EMAIL PROTECTED] tmp]# cat foo Hello World I guess this is some kind of caching effect, because strace shows that there is only a single read to the actual physical file. Maybe hostfs should check whether the outside file has changed and invalidate the cache if necessary. Cheers, Ingo ------------------------------------------------------------------------- Sponsored by: SourceForge.net Community Choice Awards: VOTE NOW! Studies have shown that voting for your favorite open source project, along with a healthy diet, reduces your potential for chronic lameness and boredom. Vote Now at http://www.sourceforge.net/community/cca08 _______________________________________________ User-mode-linux-devel mailing list User-mode-linux-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/user-mode-linux-devel
