Commit:     b5beb1caff4ce063e6e2dc13f23b80eeef4e9782
Parent:     e6f3602d2c58815775b2a293cec6650622236169
Author:     Masatake YAMATO <[EMAIL PROTECTED]>
AuthorDate: Mon Feb 4 22:29:31 2008 -0800
Committer:  Linus Torvalds <[EMAIL PROTECTED]>
CommitDate: Tue Feb 5 09:44:19 2008 -0800

    check ADVICE of fadvise64_64 even if get_xip_page is given
    I've written some test programs in ltp project.  During writing I met an
    problem which I cannot solve in user land.  So I wrote a patch for linux
    kernel.  Please, include this patch if acceptable.
    The test program tests the 4th parameter of fadvise64_64:
        long sys_fadvise64_64(int fd, loff_t offset, loff_t len, int advice);
    My test case calls fadvise64_64 with invalid advice value and checks errno 
    set to EINVAL.  About the advice parameter man page says:
        Permissible values for advice include:
           EINVAL An invalid value was specified for advice.
    However, I got a bug report that the system call invocations
    in my test case returned 0 unexpectedly.
    I've inspected the kernel code:
        asmlinkage long sys_fadvise64_64(int fd, loff_t offset, loff_t len, int 
            struct file *file = fget(fd);
            struct address_space *mapping;
            struct backing_dev_info *bdi;
            loff_t endbyte;                     /* inclusive */
            pgoff_t start_index;
            pgoff_t end_index;
            unsigned long nrpages;
            int ret = 0;
            if (!file)
                    return -EBADF;
            if (S_ISFIFO(file->f_path.dentry->d_inode->i_mode)) {
                    ret = -ESPIPE;
                    goto out;
            mapping = file->f_mapping;
            if (!mapping || len < 0) {
                    ret = -EINVAL;
                    goto out;
            if (mapping->a_ops->get_xip_page)
                    /* no bad return value, but ignore advice */
                    goto out;
            return ret;
    I found the advice parameter is just ignored in the case
    mapping->a_ops->get_xip_page is given. This behavior is different from
    what is written on the man page. Is this o.k.?
    get_xip_page is given if CONFIG_EXT2_FS_XIP is true.
    Anyway I cannot find the easy way to detect get_xip_page
    field is given or CONFIG_EXT2_FS_XIP is true from the
    user space.
    I propose the following patch which checks the advice parameter
    even if get_xip_page is given.
    Signed-off-by: Masatake YAMATO <[EMAIL PROTECTED]>
    Acked-by: Carsten Otte <[EMAIL PROTECTED]>
    Signed-off-by: Andrew Morton <[EMAIL PROTECTED]>
    Signed-off-by: Linus Torvalds <[EMAIL PROTECTED]>
 mm/fadvise.c |   16 ++++++++++++++--
 1 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/mm/fadvise.c b/mm/fadvise.c
index 0df4c89..3c0f1e9 100644
--- a/mm/fadvise.c
+++ b/mm/fadvise.c
@@ -49,9 +49,21 @@ asmlinkage long sys_fadvise64_64(int fd, loff_t offset, 
loff_t len, int advice)
                goto out;
-       if (mapping->a_ops->get_xip_page)
-               /* no bad return value, but ignore advice */
+       if (mapping->a_ops->get_xip_page) {
+               switch (advice) {
+               case POSIX_FADV_NORMAL:
+               case POSIX_FADV_RANDOM:
+               case POSIX_FADV_SEQUENTIAL:
+               case POSIX_FADV_WILLNEED:
+               case POSIX_FADV_NOREUSE:
+               case POSIX_FADV_DONTNEED:
+                       /* no bad return value, but ignore advice */
+                       break;
+               default:
+                       ret = -EINVAL;
+               }
                goto out;
+       }
        /* Careful about overflows. Len == 0 means "as much as possible" */
        endbyte = offset + len;
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