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author | npiggin@suse.de <npiggin@suse.de> | 2010-05-27 01:05:33 +1000 |
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committer | Al Viro <viro@zeniv.linux.org.uk> | 2010-05-27 22:15:33 -0400 |
commit | 7bb46a6734a7e1ad4beaecc11cae7ed3ff81d30f (patch) | |
tree | e575d9c55e2a6ccc645dcb3ae2564de458b428f2 /include/linux/buffer_head.h | |
parent | 7000d3c424e5bb350e502a477fb0e1ed42f8b10e (diff) | |
download | kernel_samsung_smdk4412-7bb46a6734a7e1ad4beaecc11cae7ed3ff81d30f.zip kernel_samsung_smdk4412-7bb46a6734a7e1ad4beaecc11cae7ed3ff81d30f.tar.gz kernel_samsung_smdk4412-7bb46a6734a7e1ad4beaecc11cae7ed3ff81d30f.tar.bz2 |
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 'include/linux/buffer_head.h')
-rw-r--r-- | include/linux/buffer_head.h | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/include/linux/buffer_head.h b/include/linux/buffer_head.h index 05e5f599..1b9ba19 100644 --- a/include/linux/buffer_head.h +++ b/include/linux/buffer_head.h @@ -203,6 +203,9 @@ int block_write_full_page_endio(struct page *page, get_block_t *get_block, int block_read_full_page(struct page*, get_block_t*); int block_is_partially_uptodate(struct page *page, read_descriptor_t *desc, unsigned long from); +int block_write_begin_newtrunc(struct file *, struct address_space *, + loff_t, unsigned, unsigned, + struct page **, void **, get_block_t*); int block_write_begin(struct file *, struct address_space *, loff_t, unsigned, unsigned, struct page **, void **, get_block_t*); @@ -214,6 +217,9 @@ int generic_write_end(struct file *, struct address_space *, struct page *, void *); void page_zero_new_buffers(struct page *page, unsigned from, unsigned to); int block_prepare_write(struct page*, unsigned, unsigned, get_block_t*); +int cont_write_begin_newtrunc(struct file *, struct address_space *, loff_t, + unsigned, unsigned, struct page **, void **, + get_block_t *, loff_t *); int cont_write_begin(struct file *, struct address_space *, loff_t, unsigned, unsigned, struct page **, void **, get_block_t *, loff_t *); @@ -225,6 +231,9 @@ void block_sync_page(struct page *); sector_t generic_block_bmap(struct address_space *, sector_t, get_block_t *); int block_truncate_page(struct address_space *, loff_t, get_block_t *); int file_fsync(struct file *, int); +int nobh_write_begin_newtrunc(struct file *, struct address_space *, + loff_t, unsigned, unsigned, + struct page **, void **, get_block_t*); int nobh_write_begin(struct file *, struct address_space *, loff_t, unsigned, unsigned, struct page **, void **, get_block_t*); |