Re: bpfilter logging write errors in dmesg

[Christoph Hellwig]

Strange.  Can you add this additional debugging patch:

diff --git a/fs/read_write.c b/fs/read_write.c
index 4fb797822567a6..d0a8ada1efd954 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -369,8 +369,10 @@ int rw_verify_area(int read_write, struct file *file, 
const loff_t *ppos, size_t
        int retval = -EINVAL;
 
        inode = file_inode(file);
-       if (unlikely((ssize_t) count < 0))
+       if (unlikely((ssize_t) count < 0)) {
+               printk("count invalid: %zd\n", count);
                return retval;
+       }
 
        /*
         * ranged mandatory locking does not apply to streams - it makes sense
@@ -380,25 +382,35 @@ int rw_verify_area(int read_write, struct file *file, 
const loff_t *ppos, size_t
                loff_t pos = *ppos;
 
                if (unlikely(pos < 0)) {
-                       if (!unsigned_offsets(file))
+                       if (!unsigned_offsets(file)) {
+                               printk("pos invalid: %lld\n", pos);
                                return retval;
+                       }
                        if (count >= -pos) /* both values are in 0..LLONG_MAX */
                                return -EOVERFLOW;
                } else if (unlikely((loff_t) (pos + count) < 0)) {
-                       if (!unsigned_offsets(file))
+                       if (!unsigned_offsets(file)) {
+                               printk("pos+count invalid: %lld, %zd\n", pos, 
count);
                                return retval;
+                       }
                }
 
                if (unlikely(inode->i_flctx && mandatory_lock(inode))) {
                        retval = locks_mandatory_area(inode, file, pos, pos + 
count - 1,
                                        read_write == READ ? F_RDLCK : F_WRLCK);
-                       if (retval < 0)
+                       if (retval < 0) {
+                               if (retval == -EINVAL)
+                                       printk("locks_mandatory_area\n");
                                return retval;
+                       }
                }
        }
 
-       return security_file_permission(file,
+       retval = security_file_permission(file,
                                read_write == READ ? MAY_READ : MAY_WRITE);
+       if (retval == -EINVAL)
+               printk("security_file_permission\n");
+       return retval;
 }
 
 static ssize_t new_sync_read(struct file *filp, char __user *buf, size_t len, 
loff_t *ppos)