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fs: remove prepare_write/commit_write

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Nothing uses prepare_write or commit_write. Remove them from the tree
completely.

[akpm@linux-foundation.org: schedule simple_prepare_write() for unexporting]
Signed-off-by: Nick Piggin <npiggin@suse.de>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Nick Piggin
2008-10-29 14:00:55 -07:00
committed by Linus Torvalds
parent 9b913735e5
commit 4e02ed4b4a
9 changed files with 23 additions and 293 deletions
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12
Documentation/filesystems/Locking
View File

@@ -161,8 +161,12 @@ prototypes:
int (*set_page_dirty)(struct page *page);
int (*readpages)(struct file *filp, struct address_space *mapping,
struct list_head *pages, unsigned nr_pages);
int (*prepare_write)(struct file *, struct page *, unsigned, unsigned);
int (*commit_write)(struct file *, struct page *, unsigned, unsigned);
int (*write_begin)(struct file *, struct address_space *mapping,
loff_t pos, unsigned len, unsigned flags,
struct page **pagep, void **fsdata);
int (*write_end)(struct file *, struct address_space *mapping,
loff_t pos, unsigned len, unsigned copied,
struct page *page, void *fsdata);
sector_t (*bmap)(struct address_space *, sector_t);
int (*invalidatepage) (struct page *, unsigned long);
int (*releasepage) (struct page *, int);
@@ -180,8 +184,6 @@ sync_page: no maybe
writepages: no
set_page_dirty no no
readpages: no
prepare_write: no yes yes
commit_write: no yes yes
write_begin: no locks the page yes
write_end: no yes, unlocks yes
perform_write: no n/a yes
@@ -191,7 +193,7 @@ releasepage: no yes
direct_IO: no
launder_page: no yes
->prepare_write(), ->commit_write(), ->sync_page() and ->readpage()
->write_begin(), ->write_end(), ->sync_page() and ->readpage()
may be called from the request handler (/dev/loop).
->readpage() unlocks the page, either synchronously or via I/O

39
Documentation/filesystems/vfs.txt
View File

@@ -492,7 +492,7 @@ written-back to storage typically in whole pages, however the
address_space has finer control of write sizes.
The read process essentially only requires 'readpage'. The write
process is more complicated and uses prepare_write/commit_write or
process is more complicated and uses write_begin/write_end or
set_page_dirty to write data into the address_space, and writepage,
sync_page, and writepages to writeback data to storage.
@@ -521,8 +521,6 @@ struct address_space_operations {
int (*set_page_dirty)(struct page *page);
int (*readpages)(struct file *filp, struct address_space *mapping,
struct list_head *pages, unsigned nr_pages);
int (*prepare_write)(struct file *, struct page *, unsigned, unsigned);
int (*commit_write)(struct file *, struct page *, unsigned, unsigned);
int (*write_begin)(struct file *, struct address_space *mapping,
loff_t pos, unsigned len, unsigned flags,
struct page **pagep, void **fsdata);
@@ -598,37 +596,7 @@ struct address_space_operations {
readpages is only used for read-ahead, so read errors are
ignored. If anything goes wrong, feel free to give up.
prepare_write: called by the generic write path in VM to set up a write
request for a page. This indicates to the address space that
the given range of bytes is about to be written. The
address_space should check that the write will be able to
complete, by allocating space if necessary and doing any other
internal housekeeping. If the write will update parts of
any basic-blocks on storage, then those blocks should be
pre-read (if they haven't been read already) so that the
updated blocks can be written out properly.
The page will be locked.
Note: the page _must not_ be marked uptodate in this function
(or anywhere else) unless it actually is uptodate right now. As
soon as a page is marked uptodate, it is possible for a concurrent
read(2) to copy it to userspace.
commit_write: If prepare_write succeeds, new data will be copied
into the page and then commit_write will be called. It will
typically update the size of the file (if appropriate) and
mark the inode as dirty, and do any other related housekeeping
operations. It should avoid returning an error if possible -
errors should have been handled by prepare_write.
write_begin: This is intended as a replacement for prepare_write. The
key differences being that:
- it returns a locked page (in *pagep) rather than being
given a pre locked page;
- it must be able to cope with short writes (where the
length passed to write_begin is greater than the number
of bytes copied into the page).
write_begin:
Called by the generic buffered write code to ask the filesystem to
prepare to write len bytes at the given offset in the file. The
address_space should check that the write will be able to complete,
@@ -640,6 +608,9 @@ struct address_space_operations {
The filesystem must return the locked pagecache page for the specified
offset, in *pagep, for the caller to write into.
It must be able to cope with short writes (where the length passed to
write_begin is greater than the number of bytes copied into the page).
flags is a field for AOP_FLAG_xxx flags, described in
include/linux/fs.h.