On 06/27/2011 02:02 PM, Josef Bacik wrote: > This just gets us ready to support the SEEK_HOLE and SEEK_DATA flags. Turns out > using fiemap in things like cp cause more problems than it solves, so lets try > and give userspace an interface that doesn't suck. We need to match solaris > here, and the definitions are > > *o* If /whence/ is SEEK_HOLE, the offset of the start of the > next hole greater than or equal to the supplied offset > is returned. The definition of a hole is provided near > the end of the DESCRIPTION. > > *o* If /whence/ is SEEK_DATA, the file pointer is set to the > start of the next non-hole file region greater than or > equal to the supplied offset. > > So in the generic case the entire file is data and there is a virtual hole at > the end. That means we will just return i_size for SEEK_HOLE and will return > the same offset for SEEK_DATA. This is how Solaris does it so we have to do it > the same way. > > Thanks, > > Signed-off-by: Josef Bacik <josef@xxxxxxxxxx> > --- > fs/read_write.c | 37 +++++++++++++++++++++++++++++++++++++ > include/linux/fs.h | 4 +++- > 2 files changed, 40 insertions(+), 1 deletions(-) > > diff --git a/fs/read_write.c b/fs/read_write.c > index 5520f8a..d58551e 100644 > --- a/fs/read_write.c > +++ b/fs/read_write.c > @@ -64,6 +64,23 @@ generic_file_llseek_unlocked(struct file *file, loff_t offset, int origin) > return file->f_pos; > offset += file->f_pos; > break; > + case SEEK_DATA: > + /* > + * In the generic case the entire file is data, so as long as > + * offset isn't at the end of the file then the offset is data. > + */ > + if (offset >= inode->i_size) > + return -ENXIO; > + break; > + case SEEK_HOLE: > + /* > + * There is a virtual hole at the end of the file, so as long as > + * offset isn't i_size or larger, return i_size. > + */ > + if (offset >= inode->i_size) > + return -ENXIO; > + offset = inode->i_size; > + break; > } > > if (offset < 0 && !unsigned_offsets(file)) > @@ -141,6 +158,26 @@ loff_t default_llseek(struct file *file, loff_t offset, int origin) > goto out; > } > offset += file->f_pos; > + break; > + case SEEK_DATA: > + /* > + * In the generic case the entire file is data, so as > + * long as offset isn't at the end of the file then the > + * offset is data. > + */ > + if (offset >= inode->i_size) > + return -ENXIO; > + break; > + case SEEK_HOLE: > + /* > + * There is a virtual hole at the end of the file, so > + * as long as offset isn't i_size or larger, return > + * i_size. > + */ > + if (offset >= inode->i_size) > + return -ENXIO; > + offset = inode->i_size; > + break; Hrm sorry I just noticed this doesn't compile. I'll fix it up and resend along with the xfstest update that Andreas pointed out. Thanks, Josef -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
