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authorNick Piggin <npiggin@suse.de>2008-10-29 14:00:55 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2008-10-30 11:38:45 -0700
commit4e02ed4b4a2fae34aae766a5bb93ae235f60adb8 (patch)
treebddfb61b7cc4a4007ae176ccb1ace5740b61da8d /Documentation/filesystems/vfs.txt
parent9b913735e53ab0da4a792bac0de8e178cc13dcfb (diff)
fs: remove prepare_write/commit_write
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>
Diffstat (limited to 'Documentation/filesystems/vfs.txt')
-rw-r--r--Documentation/filesystems/vfs.txt39
1 files changed, 5 insertions, 34 deletions
diff --git a/Documentation/filesystems/vfs.txt b/Documentation/filesystems/vfs.txt
index c4d348dabe9..5579bda58a6 100644
--- a/Documentation/filesystems/vfs.txt
+++ b/Documentation/filesystems/vfs.txt
@@ -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.