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authorJeff Layton <jlayton@redhat.com>2009-09-18 13:05:53 -0700
committerAl Viro <viro@zeniv.linux.org.uk>2009-09-24 07:47:33 -0400
commit42cb56ae2ab67390da34906b27bedc3f2ff1393b (patch)
treedb4a6a4871feeb153f924a80a79b7790e4e2c90e
parent5aa98b706e83da4cde4172c890d6e815915536a0 (diff)
downloadlinux-42cb56ae2ab67390da34906b27bedc3f2ff1393b.tar.bz2
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.c10
-rw-r--r--include/linux/fs.h2
2 files changed, 11 insertions, 1 deletions
diff --git a/fs/super.c b/fs/super.c
index 0e7207b9815c..4906e2d8f400 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 955e34615cb7..cbb7724c11d3 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;