From: Josef Bacik Date: Wed, 5 Jan 2011 20:00:07 +0000 (-0500) Subject: fs: add documentation on fallocate hole punching X-Git-Tag: v2.6.38-rc1~237^2 X-Git-Url: https://openfabrics.org/gitweb/?a=commitdiff_plain;h=924241575a85249b9d410e38f5b2fcad9035e45c;p=~shefty%2Frdma-dev.git fs: add documentation on fallocate hole punching This patch simply adds documentation on how to handle the hole punching mode of fallocate for any filesystem wishing to use it. Signed-off-by: Josef Bacik Signed-off-by: Al Viro --- diff --git a/Documentation/filesystems/porting b/Documentation/filesystems/porting index 07a32b42cf9..266d2059b9b 100644 --- a/Documentation/filesystems/porting +++ b/Documentation/filesystems/porting @@ -385,3 +385,12 @@ Documentation/filesystems/vfs.txt for more details. on many or all directory inodes on the way down a path walk (to check for exec permission). These must now be rcu-walk aware (flags & IPERM_RCU). See Documentation/filesystems/vfs.txt for more details. + +-- +[mandatory] + In ->fallocate() you must check the mode option passed in. If your +filesystem does not support hole punching (deallocating space in the middle of a +file) you must return -EOPNOTSUPP if FALLOC_FL_PUNCH_HOLE is set in mode. +Currently you can only have FALLOC_FL_PUNCH_HOLE with FALLOC_FL_KEEP_SIZE set, +so the i_size should not change when hole punching, even when puching the end of +a file off.