• jan Blunck's avatar
    fs/: do not fallback to default_llseek() when readdir() uses BKL · ca572727
    jan Blunck authored
    Do not use the fallback default_llseek() if the readdir operation of the
    filesystem still uses the big kernel lock.
    
    Since llseek() modifies
    file->f_pos of the directory directly it may need locking to not confuse
    readdir which usually uses file->f_pos directly as well
    
    Since the special characteristics of the BKL (unlocked on schedule) are
    not necessary in this case, the inode mutex can be used for locking as
    provided by generic_file_llseek().  This is only possible since all
    filesystems, except reiserfs, either use a directory as a flat file or
    with disk address offsets.  Reiserfs on the other hand uses a 32bit hash
    off the filename as the offset so generic_file_llseek() can get used as
    well since the hash is always smaller than sb->s_maxbytes (= (512 << 32) -
    blocksize).
    Signed-off-by: default avatarJan Blunck <jblunck@suse.de>
    Acked-by: default avatarJan Kara <jack@suse.cz>
    Acked-by: default avatarAnders Larsen <al@alarsen.net>
    Cc: Frederic Weisbecker <fweisbec@gmail.com>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    ca572727
dir.c 8.89 KB