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authornpiggin@suse.de <npiggin@suse.de>2010-05-27 01:05:33 +1000
committerAl Viro <viro@zeniv.linux.org.uk>2010-05-27 22:15:33 -0400
commit7bb46a6734a7e1ad4beaecc11cae7ed3ff81d30f (patch)
treee575d9c55e2a6ccc645dcb3ae2564de458b428f2 /mm
parent7000d3c424e5bb350e502a477fb0e1ed42f8b10e (diff)
downloadlinux-2.6.34-ux500-7bb46a6734a7e1ad4beaecc11cae7ed3ff81d30f.tar.gz
fs: introduce new truncate sequence
Introduce a new truncate calling sequence into fs/mm subsystems. Rather than setattr > vmtruncate > truncate, have filesystems call their truncate sequence from ->setattr if filesystem specific operations are required. vmtruncate is deprecated, and truncate_pagecache and inode_newsize_ok helpers introduced previously should be used. simple_setattr is introduced for simple in-ram filesystems to implement the new truncate sequence. Eventually all filesystems should be converted to implement a setattr, and the default code in notify_change should go away. simple_setsize is also introduced to perform just the ATTR_SIZE portion of simple_setattr (ie. changing i_size and trimming pagecache). To implement the new truncate sequence: - filesystem specific manipulations (eg freeing blocks) must be done in the setattr method rather than ->truncate. - vmtruncate can not be used by core code to trim blocks past i_size in the event of write failure after allocation, so this must be performed in the fs code. - convert usage of helpers block_write_begin, nobh_write_begin, cont_write_begin, and *blockdev_direct_IO* to use _newtrunc postfixed variants. These avoid calling vmtruncate to trim blocks (see previous). - inode_setattr should not be used. generic_setattr is a new function to be used to copy simple attributes into the generic inode. - make use of the better opportunity to handle errors with the new sequence. Big problem with the previous calling sequence: the filesystem is not called until i_size has already changed. This means it is not allowed to fail the call, and also it does not know what the previous i_size was. Also, generic code calling vmtruncate to truncate allocated blocks in case of error had no good way to return a meaningful error (or, for example, atomically handle block deallocation). Cc: Christoph Hellwig <hch@lst.de> Acked-by: Jan Kara <jack@suse.cz> Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'mm')
-rw-r--r--mm/truncate.c10
1 files changed, 5 insertions, 5 deletions
diff --git a/mm/truncate.c b/mm/truncate.c
index f42675a3615..937571b8b23 100644
--- a/mm/truncate.c
+++ b/mm/truncate.c
@@ -548,18 +548,18 @@ EXPORT_SYMBOL(truncate_pagecache);
* NOTE! We have to be ready to update the memory sharing
* between the file and the memory map for a potential last
* incomplete page. Ugly, but necessary.
+ *
+ * This function is deprecated and simple_setsize or truncate_pagecache
+ * should be used instead.
*/
int vmtruncate(struct inode *inode, loff_t offset)
{
- loff_t oldsize;
int error;
- error = inode_newsize_ok(inode, offset);
+ error = simple_setsize(inode, offset);
if (error)
return error;
- oldsize = inode->i_size;
- i_size_write(inode, offset);
- truncate_pagecache(inode, oldsize, offset);
+
if (inode->i_op->truncate)
inode->i_op->truncate(inode);