Commit f4e6d844 authored by Matthew Wilcox's avatar Matthew Wilcox Committed by Al Viro

Remove last traces of ->sync_page

Commit 7eaceacc removed ->sync_page, but a few mentions of it still
existed in documentation and comments,
Signed-off-by: default avatarMatthew Wilcox <>
Signed-off-by: default avatarAl Viro <>
parent d4c91a8f
......@@ -1024,8 +1024,7 @@ could be on demand. For example wait_on_buffer sets the unplugging going
through sync_buffer() running blk_run_address_space(mapping). Or the caller
can do it explicity through blk_unplug(bdev). So in the read case,
the queue gets explicitly unplugged as part of waiting for completion on that
buffer. For page driven IO, the address space ->sync_page() takes care of
doing the blk_run_address_space().
This is kind of controversial territory, as it's not clear if plugging is
......@@ -179,7 +179,6 @@ unlocks and drops the reference.
int (*writepage)(struct page *page, struct writeback_control *wbc);
int (*readpage)(struct file *, struct page *);
int (*sync_page)(struct page *);
int (*writepages)(struct address_space *, struct writeback_control *);
int (*set_page_dirty)(struct page *page);
int (*readpages)(struct file *filp, struct address_space *mapping,
......@@ -208,7 +207,6 @@ locking rules:
PageLocked(page) i_mutex
writepage: yes, unlocks (see below)
readpage: yes, unlocks
sync_page: maybe
set_page_dirty no
......@@ -226,8 +224,8 @@ error_remove_page: yes
swap_activate: no
swap_deactivate: no
->write_begin(), ->write_end(), ->sync_page() and ->readpage()
may be called from the request handler (/dev/loop).
->write_begin(), ->write_end() and ->readpage() may be called from
the request handler (/dev/loop).
->readpage() unlocks the page, either synchronously or via I/O
......@@ -283,11 +281,6 @@ will leave the page itself marked clean but it will be tagged as dirty in the
radix tree. This incoherency can lead to all sorts of hard-to-debug problems
in the filesystem like having dirty inodes at umount and losing written data.
->sync_page() locking rules are not well-defined - usually it is called
with lock on page, but that is not guaranteed. Considering the currently
existing instances of this method ->sync_page() itself doesn't look
->writepages() is used for periodic writeback and for syscall-initiated
sync operations. The address_space should start I/O against at least
*nr_to_write pages. *nr_to_write must be decremented for each page which is
......@@ -534,9 +534,7 @@ __sync_single_inode) to check if ->writepages has been successful in
writing out the whole address_space.
The Writeback tag is used by filemap*wait* and sync_page* functions,
via filemap_fdatawait_range, to wait for all writeback to
complete. While waiting ->sync_page (if defined) will be called on
each page that is found to require writeback.
via filemap_fdatawait_range, to wait for all writeback to complete.
An address_space handler may attach extra information to a page,
typically using the 'private' field in the 'struct page'. If such
......@@ -554,8 +552,8 @@ address_space has finer control of write sizes.
The read process essentially only requires 'readpage'. The write
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.
set_page_dirty to write data into the address_space, and writepage
and writepages to writeback data to storage.
Adding and removing pages to/from an address_space is protected by the
inode's i_mutex.
......@@ -361,7 +361,6 @@ static int zisofs_readpage(struct file *file, struct page *page)
const struct address_space_operations zisofs_aops = {
.readpage = zisofs_readpage,
/* No sync_page operation supported? */
/* No bmap operation supported */
......@@ -1854,7 +1854,7 @@ int ntfs_read_inode_mount(struct inode *vi)
/* Need this to sanity check attribute list references to $MFT. */
vi->i_generation = ni->seq_no = le16_to_cpu(m->sequence_number);
/* Provides readpage() and sync_page() for map_mft_record(). */
/* Provides readpage() for map_mft_record(). */
vi->i_mapping->a_ops = &ntfs_mst_aops;
ctx = ntfs_attr_get_search_ctx(ni, m);
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