diff options
| author | Jeff Layton <jlayton@redhat.com> | 2009-09-18 13:05:53 -0700 |
|---|---|---|
| committer | Al Viro <viro@zeniv.linux.org.uk> | 2009-09-24 07:47:33 -0400 |
| commit | 42cb56ae2ab67390da34906b27bedc3f2ff1393b (patch) | |
| tree | db4a6a4871feeb153f924a80a79b7790e4e2c90e | |
| parent | 5aa98b706e83da4cde4172c890d6e815915536a0 (diff) | |
vfs: change sb->s_maxbytes to a loff_t
sb->s_maxbytes is supposed to indicate the maximum size of a file that can
exist on the filesystem. It's declared as an unsigned long long.
Even if a filesystem has no inherent limit that prevents it from using
every bit in that unsigned long long, it's still problematic to set it to
anything larger than MAX_LFS_FILESIZE. There are places in the kernel
that cast s_maxbytes to a signed value. If it's set too large then this
cast makes it a negative number and generally breaks the comparison.
Change s_maxbytes to be loff_t instead. That should help eliminate the
temptation to set it too large by making it a signed value.
Also, add a warning for couple of releases to help catch filesystems that
set s_maxbytes too large. Eventually we can either convert this to a
BUG() or just remove it and in the hope that no one will get it wrong now
that it's a signed value.
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Robert Love <rlove@google.com>
Cc: Mandeep Singh Baines <msb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
| -rw-r--r-- | fs/super.c | 10 | ||||
| -rw-r--r-- | include/linux/fs.h | 2 |
2 files changed, 11 insertions, 1 deletions
diff --git a/fs/super.c b/fs/super.c index 0e7207b9815..4906e2d8f40 100644 --- a/fs/super.c +++ b/fs/super.c @@ -892,6 +892,16 @@ vfs_kern_mount(struct file_system_type *type, int flags, const char *name, void if (error) goto out_sb; + /* + * filesystems should never set s_maxbytes larger than MAX_LFS_FILESIZE + * but s_maxbytes was an unsigned long long for many releases. Throw + * this warning for a little while to try and catch filesystems that + * violate this rule. This warning should be either removed or + * converted to a BUG() in 2.6.34. + */ + WARN((mnt->mnt_sb->s_maxbytes < 0), "%s set sb->s_maxbytes to " + "negative value (%lld)\n", type->name, mnt->mnt_sb->s_maxbytes); + mnt->mnt_mountpoint = mnt->mnt_root; mnt->mnt_parent = mnt; up_write(&mnt->mnt_sb->s_umount); diff --git a/include/linux/fs.h b/include/linux/fs.h index 955e34615cb..cbb7724c11d 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -1315,7 +1315,7 @@ struct super_block { unsigned long s_blocksize; unsigned char s_blocksize_bits; unsigned char s_dirt; - unsigned long long s_maxbytes; /* Max file size */ + loff_t s_maxbytes; /* Max file size */ struct file_system_type *s_type; const struct super_operations *s_op; const struct dquot_operations *dq_op; |