On Tue, 18 Feb 2014, Dave Chinner wrote: > Date: Tue, 18 Feb 2014 13:51:12 +1100 > From: Dave Chinner <david@xxxxxxxxxxxxx> > To: Lukas Czerner <lczerner@xxxxxxxxxx> > Cc: linux-ext4@xxxxxxxxxxxxxxx, linux-fsdevel@xxxxxxxxxxxxxxx, tytso@xxxxxxx, > xfs@xxxxxxxxxxx > Subject: Re: [PATCH 4/6] fs: Introduce FALLOC_FL_ZERO_RANGE flag for fallocate > > On Mon, Feb 17, 2014 at 04:08:21PM +0100, Lukas Czerner wrote: > > Introduce new FALLOC_FL_ZERO_RANGE flag for fallocate. This has the same > > functionality as xfs ioctl XFS_IOC_ZERO_RANGE. > > > > It can be used to convert a range of file to zeros preferably without > > issuing data IO. Blocks should be preallocated for the regions that span > > holes in the file, and the entire range is preferable converted to > > unwritten extents - even though file system may choose to zero out the > > extent or do whatever which will result in reading zeros from the range > > while the range remains allocated for the file. > > > > This can be also used to preallocate blocks past EOF in the same way as > > with fallocate. Flag FALLOC_FL_KEEP_SIZE which should cause the inode > > size to remain the same. > > > > Signed-off-by: Lukas Czerner <lczerner@xxxxxxxxxx> > > --- > > fs/open.c | 7 ++++++- > > include/uapi/linux/falloc.h | 1 + > > 2 files changed, 7 insertions(+), 1 deletion(-) > > > > diff --git a/fs/open.c b/fs/open.c > > index 4b3e1ed..6dc46c1 100644 > > --- a/fs/open.c > > +++ b/fs/open.c > > @@ -231,7 +231,12 @@ int do_fallocate(struct file *file, int mode, loff_t offset, loff_t len) > > return -EINVAL; > > > > /* Return error if mode is not supported */ > > - if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE)) > > + if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE | > > + FALLOC_FL_ZERO_RANGE)) > > + return -EOPNOTSUPP; > > + > > + /* Punch hole and zero range are mutually exclusive */ > > + if (mode & FALLOC_FL_PUNCH_HOLE && mode & FALLOC_FL_ZERO_RANGE) > > I would have expected gcc to throw a warning on this. Even if it > doesn't, it's so easy to mix up & an && and & it needs parenthesis > around it to make it obvious what you actually meant and it doesn't > have a && where an & should be or vice versa. Better, IMO, is this: > > /* Punch hole and zero range are mutually exclusive */ > if ((mode & (FALLOC_FL_PUNCH_HOLE | FALLOC_FL_ZERO_RANGE)) == > (FALLOC_FL_PUNCH_HOLE | FALLOC_FL_ZERO_RANGE)) > return -EOPNOTSUPP; > > because it's obvious what the intent is and easy to spot typos. Fair enough, I'll change it. Thanks! -Lukas > > Cheers, > > Dave. > -- 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
