lkml.org 
[lkml]   [2008]   [Feb]   [18]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    SubjectRe: [PATCH 09/30] r/o bind mounts: drop write during emergency remount
    From
    Date
    > The emergency remount code forcibly removes FMODE_WRITE from
    > filps. The r/o bind mount code notices that this was done
    > without a proper mnt_drop_write() and properly gives a
    > warning.
    >
    > This patch does a mnt_drop_write() to keep everything
    > balanced.
    >
    > Acked-by: Al Viro <viro@ZenIV.linux.org.uk>
    > Signed-off-by: Christoph Hellwig <hch@infradead.org>
    > Signed-off-by: Dave Hansen <haveblue@us.ibm.com>
    > ---
    >
    > linux-2.6.git-dave/fs/super.c | 20 ++++++++++++++++++--
    > 1 file changed, 18 insertions(+), 2 deletions(-)
    >
    > diff -puN fs/super.c~robind-sysrq-fix fs/super.c
    > --- linux-2.6.git/fs/super.c~robind-sysrq-fix 2008-02-15 13:25:46.000000000 -0800
    > +++ linux-2.6.git-dave/fs/super.c 2008-02-15 13:25:46.000000000 -0800
    > @@ -37,6 +37,7 @@
    > #include <linux/idr.h>
    > #include <linux/kobject.h>
    > #include <linux/mutex.h>
    > +#include <linux/file.h>
    > #include <asm/uaccess.h>
    >
    >
    > @@ -567,10 +568,25 @@ static void mark_files_ro(struct super_b
    > {
    > struct file *f;
    >
    > +retry:
    > file_list_lock();
    > list_for_each_entry(f, &sb->s_files, f_u.fu_list) {
    > - if (S_ISREG(f->f_path.dentry->d_inode->i_mode) && file_count(f))
    > - f->f_mode &= ~FMODE_WRITE;
    > + struct vfsmount *mnt;
    > + if (!S_ISREG(f->f_path.dentry->d_inode->i_mode))
    > + continue;
    > + if (!file_count(f))
    > + continue;
    > + if (!(f->f_mode & FMODE_WRITE))
    > + continue;
    > + f->f_mode &= ~FMODE_WRITE;
    > + mnt = f->f_path.mnt;

    AFAICS an mntget() is needed here to make sure mnt doesn't go away
    after releasing file_list_lock.

    Miklos

    > + file_list_unlock();
    > + /*
    > + * This can sleep, so we can't hold
    > + * the file_list_lock() spinlock.
    > + */
    > + mnt_drop_write(mnt);
    > + goto retry;
    > }
    > file_list_unlock();
    > }
    > _
    >


    \
     
     \ /
      Last update: 2008-02-18 17:31    [W:0.033 / U:2.120 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site