• Mingming Cao's avatar
    fix ext4/JBD2 build warnings · b38bd33a
    Mingming Cao authored
    Looking at the current linus-git tree jbd_debug() define in
    include/linux/jbd2.h
    
    extern u8 journal_enable_debug;
    
    #define jbd_debug(n, f, a...)                                           \
            do {                                                            \
                    if ((n) <= journal_enable_debug) {                      \
                            printk (KERN_DEBUG "(%s, %d): %s: ",            \
                                    __FILE__, __LINE__, __FUNCTION__);      \
                            printk (f, ## a);                               \
                    }                                                       \
            } while (0)
    > fs/ext4/inode.c: In function ‘ext4_write_inode’:
    > fs/ext4/inode.c:2906: warning: comparison is always true due to limited
    > range of data type
    >
    > fs/jbd2/recovery.c: In function ‘jbd2_journal_recover’:
    > fs/jbd2/recovery.c:254: warning: comparison is always true due to
    > limited range of data type
    > fs/jbd2/recovery.c:257: warning: comparison is always true due to
    > limited range of data type
    >
    > fs/jbd2/recovery.c: In function ‘jbd2_journal_skip_recovery’:
    > fs/jbd2/recovery.c:301: warning: comparison is always true due to
    > limited range of data type
    >
    Noticed all warnings are occurs when the debug level is 0. Then found
    the "jbd2: Move jbd2-debug file to debugfs" patch
    http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=0f49d5d019afa4e94253bfc92f0daca3badb990b
    
    changed the jbd2_journal_enable_debug from int type to u8, makes the
    jbd_debug comparision is always true when the debugging level is 0. Thus
    the compile warning occurs.
    
    Thought about changing the jbd2_journal_enable_debug data type back to
    int, but can't, because the jbd2-debug is moved to debug fs, where
    calling debugfs_create_u8() to create the debugfs entry needs the value
    to be u8 type.
    
    Even if we changed the data type back to int, the code is still buggy,
    kernel should not print jbd2 debug message if the
    jbd2_journal_enable_debug is set to 0. But this is not the case.
    
    The fix is change the level of debugging to 1. The same should fixed in
    ext3/JBD, but currently ext3 jbd-debug via /proc fs is broken, so we
    probably should fix it all together.
    Signed-off-by: default avatarMingming Cao <cmm@us.ibm.com>
    Cc: Jeff Garzik <jeff@garzik.org>
    Cc: Theodore Tso <tytso@mit.edu>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    b38bd33a
recovery.c 15 KB