[lkml]   [1998]   [Feb]   [2]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
    SubjectRe: Some questions
    > 2> Whie mounting a fs readonly,  the kernel will set all dir perms etc. to
    > r--- for root. How does it decide user perms while mounting the fs with
    > home directories? Cud u direct me to the appropriate kernel code in this
    > case ?

    What file system are you using? I believe ext2 would always display
    the permissions that are stored on the disk. This can be seen
    in fs/ext2/inode.c:ext2_read_inode.

    > 3 > How exactly doees unlink".") work? What I feel is that the dir is
    > unlinked but the inode is still active(refcnt>10 and process is able to
    > acces the dir. as before until it exists. But what happemns if he now
    > executes the pwd ccommand?

    The VFS executes the per-fs unlink operation, but keeps the dcache
    entries (at least in Linux 2.1). The inode won't be released until
    the VFS calls the delete_inode operation, which is not called until
    the last process releases the dentry.

    What pwd would do depends on the implementation of pwd :-) Some shells
    cache the path, and don't do any system calls. When they do so (e.g.
    /bin/pwd), they call getcwd(3). In the current C library, this will try
    to travers .., ../.., ../../.. etc, and try to find the cwd step by
    step. If the current directory is unlinked, this will fail.
    Future implementations might consider /proc/self/cwd instead.

    > 4 > How does the mkdir command work exactly?

    mkdir(1) invokes mkdir(2). This, in turn, invokes a file-system
    dependent operation. On ext2, you can see the code in


     \ /
      Last update: 2005-03-22 13:41    [W:0.019 / U:0.408 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site