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>
This commit is contained in:
Nick Piggin
Linus Torvalds
Родитель
9b913735e5
Коммит
4e02ed4b4a
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@ -161,8 +161,12 @@ prototypes:
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int (*set_page_dirty)(struct page *page);
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int (*readpages)(struct file *filp, struct address_space *mapping,
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struct list_head *pages, unsigned nr_pages);
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int (*prepare_write)(struct file *, struct page *, unsigned, unsigned);
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int (*commit_write)(struct file *, struct page *, unsigned, unsigned);
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int (*write_begin)(struct file *, struct address_space *mapping,
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loff_t pos, unsigned len, unsigned flags,
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struct page **pagep, void **fsdata);
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int (*write_end)(struct file *, struct address_space *mapping,
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loff_t pos, unsigned len, unsigned copied,
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struct page *page, void *fsdata);
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sector_t (*bmap)(struct address_space *, sector_t);
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int (*invalidatepage) (struct page *, unsigned long);
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int (*releasepage) (struct page *, int);
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@ -180,8 +184,6 @@ sync_page: no maybe
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writepages: no
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set_page_dirty no no
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readpages: no
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prepare_write: no yes yes
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commit_write: no yes yes
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write_begin: no locks the page yes
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write_end: no yes, unlocks yes
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perform_write: no n/a yes
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@ -191,7 +193,7 @@ releasepage: no yes
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direct_IO: no
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launder_page: no yes
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->prepare_write(), ->commit_write(), ->sync_page() and ->readpage()
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->write_begin(), ->write_end(), ->sync_page() and ->readpage()
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may be called from the request handler (/dev/loop).
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->readpage() unlocks the page, either synchronously or via I/O
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@ -492,7 +492,7 @@ written-back to storage typically in whole pages, however the
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address_space has finer control of write sizes.
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The read process essentially only requires 'readpage'. The write
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process is more complicated and uses prepare_write/commit_write or
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process is more complicated and uses write_begin/write_end or
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set_page_dirty to write data into the address_space, and writepage,
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sync_page, and writepages to writeback data to storage.
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@ -521,8 +521,6 @@ struct address_space_operations {
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int (*set_page_dirty)(struct page *page);
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int (*readpages)(struct file *filp, struct address_space *mapping,
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struct list_head *pages, unsigned nr_pages);
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int (*prepare_write)(struct file *, struct page *, unsigned, unsigned);
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int (*commit_write)(struct file *, struct page *, unsigned, unsigned);
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int (*write_begin)(struct file *, struct address_space *mapping,
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loff_t pos, unsigned len, unsigned flags,
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struct page **pagep, void **fsdata);
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@ -598,37 +596,7 @@ struct address_space_operations {
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readpages is only used for read-ahead, so read errors are
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ignored. If anything goes wrong, feel free to give up.
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prepare_write: called by the generic write path in VM to set up a write
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request for a page. This indicates to the address space that
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the given range of bytes is about to be written. The
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address_space should check that the write will be able to
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complete, by allocating space if necessary and doing any other
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internal housekeeping. If the write will update parts of
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any basic-blocks on storage, then those blocks should be
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pre-read (if they haven't been read already) so that the
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updated blocks can be written out properly.
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The page will be locked.
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Note: the page _must not_ be marked uptodate in this function
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(or anywhere else) unless it actually is uptodate right now. As
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soon as a page is marked uptodate, it is possible for a concurrent
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read(2) to copy it to userspace.
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commit_write: If prepare_write succeeds, new data will be copied
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into the page and then commit_write will be called. It will
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typically update the size of the file (if appropriate) and
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mark the inode as dirty, and do any other related housekeeping
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operations. It should avoid returning an error if possible -
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errors should have been handled by prepare_write.
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write_begin: This is intended as a replacement for prepare_write. The
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key differences being that:
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- it returns a locked page (in *pagep) rather than being
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given a pre locked page;
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- it must be able to cope with short writes (where the
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length passed to write_begin is greater than the number
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of bytes copied into the page).
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write_begin:
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Called by the generic buffered write code to ask the filesystem to
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prepare to write len bytes at the given offset in the file. The
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address_space should check that the write will be able to complete,
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@ -640,6 +608,9 @@ struct address_space_operations {
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The filesystem must return the locked pagecache page for the specified
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offset, in *pagep, for the caller to write into.
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It must be able to cope with short writes (where the length passed to
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write_begin is greater than the number of bytes copied into the page).
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flags is a field for AOP_FLAG_xxx flags, described in
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include/linux/fs.h.
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@ -40,8 +40,7 @@
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* Heinz Mauelshagen <mge@sistina.com>, Feb 2002
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*
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* Support for falling back on the write file operation when the address space
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* operations prepare_write and/or commit_write are not available on the
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* backing filesystem.
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* operations write_begin is not available on the backing filesystem.
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* Anton Altaparmakov, 16 Feb 2005
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*
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* Still To Fix:
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@ -765,7 +764,7 @@ static int loop_set_fd(struct loop_device *lo, fmode_t mode,
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*/
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if (!file->f_op->splice_read)
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goto out_putf;
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if (aops->prepare_write || aops->write_begin)
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if (aops->write_begin)
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lo_flags |= LO_FLAGS_USE_AOPS;
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if (!(lo_flags & LO_FLAGS_USE_AOPS) && !file->f_op->write)
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lo_flags |= LO_FLAGS_READ_ONLY;
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@ -175,7 +175,7 @@ static ssize_t fat_direct_IO(int rw, struct kiocb *iocb,
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if (rw == WRITE) {
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/*
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* FIXME: blockdev_direct_IO() doesn't use ->prepare_write(),
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* FIXME: blockdev_direct_IO() doesn't use ->write_begin(),
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* so we need to update the ->mmu_private to block boundary.
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*
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* But we must fill the remaining area or hole by nul for
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@ -814,7 +814,7 @@ EXPORT_SYMBOL(simple_getattr);
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EXPORT_SYMBOL(simple_link);
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EXPORT_SYMBOL(simple_lookup);
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EXPORT_SYMBOL(simple_pin_fs);
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EXPORT_SYMBOL(simple_prepare_write);
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EXPORT_UNUSED_SYMBOL(simple_prepare_write);
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EXPORT_SYMBOL(simple_readpage);
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EXPORT_SYMBOL(simple_release_fs);
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EXPORT_SYMBOL(simple_rename);
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@ -679,8 +679,7 @@ leave:
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/* Some parts of this taken from generic_cont_expand, which turned out
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* to be too fragile to do exactly what we need without us having to
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* worry about recursive locking in ->prepare_write() and
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* ->commit_write(). */
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* worry about recursive locking in ->write_begin() and ->write_end(). */
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static int ocfs2_write_zero_page(struct inode *inode,
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u64 size)
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{
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@ -731,8 +731,8 @@ ssize_t splice_from_pipe(struct pipe_inode_info *pipe, struct file *out,
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};
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/*
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* The actor worker might be calling ->prepare_write and
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* ->commit_write. Most of the time, these expect i_mutex to
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* The actor worker might be calling ->write_begin and
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* ->write_end. Most of the time, these expect i_mutex to
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* be held. Since this may result in an ABBA deadlock with
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* pipe->inode, we have to order lock acquiry here.
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*/
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@ -489,13 +489,6 @@ struct address_space_operations {
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int (*readpages)(struct file *filp, struct address_space *mapping,
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struct list_head *pages, unsigned nr_pages);
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/*
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* ext3 requires that a successful prepare_write() call be followed
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* by a commit_write() call - they must be balanced
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*/
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int (*prepare_write)(struct file *, struct page *, unsigned, unsigned);
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int (*commit_write)(struct file *, struct page *, unsigned, unsigned);
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int (*write_begin)(struct file *, struct address_space *mapping,
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loff_t pos, unsigned len, unsigned flags,
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struct page **pagep, void **fsdata);
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236
mm/filemap.c
236
mm/filemap.c
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@ -2029,48 +2029,8 @@ int pagecache_write_begin(struct file *file, struct address_space *mapping,
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{
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const struct address_space_operations *aops = mapping->a_ops;
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if (aops->write_begin) {
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return aops->write_begin(file, mapping, pos, len, flags,
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pagep, fsdata);
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} else {
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int ret;
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pgoff_t index = pos >> PAGE_CACHE_SHIFT;
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unsigned offset = pos & (PAGE_CACHE_SIZE - 1);
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struct inode *inode = mapping->host;
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struct page *page;
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again:
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page = __grab_cache_page(mapping, index);
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*pagep = page;
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if (!page)
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return -ENOMEM;
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if (flags & AOP_FLAG_UNINTERRUPTIBLE && !PageUptodate(page)) {
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/*
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* There is no way to resolve a short write situation
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* for a !Uptodate page (except by double copying in
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* the caller done by generic_perform_write_2copy).
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*
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* Instead, we have to bring it uptodate here.
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*/
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ret = aops->readpage(file, page);
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page_cache_release(page);
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if (ret) {
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if (ret == AOP_TRUNCATED_PAGE)
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goto again;
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return ret;
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}
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goto again;
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}
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ret = aops->prepare_write(file, page, offset, offset+len);
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if (ret) {
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unlock_page(page);
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page_cache_release(page);
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if (pos + len > inode->i_size)
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vmtruncate(inode, inode->i_size);
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}
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return ret;
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}
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}
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EXPORT_SYMBOL(pagecache_write_begin);
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@ -2079,32 +2039,9 @@ int pagecache_write_end(struct file *file, struct address_space *mapping,
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struct page *page, void *fsdata)
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{
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const struct address_space_operations *aops = mapping->a_ops;
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int ret;
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if (aops->write_end) {
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mark_page_accessed(page);
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ret = aops->write_end(file, mapping, pos, len, copied,
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page, fsdata);
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} else {
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unsigned offset = pos & (PAGE_CACHE_SIZE - 1);
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struct inode *inode = mapping->host;
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flush_dcache_page(page);
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ret = aops->commit_write(file, page, offset, offset+len);
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unlock_page(page);
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mark_page_accessed(page);
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page_cache_release(page);
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if (ret < 0) {
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if (pos + len > inode->i_size)
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vmtruncate(inode, inode->i_size);
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} else if (ret > 0)
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ret = min_t(size_t, copied, ret);
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else
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ret = copied;
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}
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return ret;
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return aops->write_end(file, mapping, pos, len, copied, page, fsdata);
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}
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EXPORT_SYMBOL(pagecache_write_end);
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@ -2226,174 +2163,6 @@ repeat:
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}
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EXPORT_SYMBOL(__grab_cache_page);
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static ssize_t generic_perform_write_2copy(struct file *file,
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struct iov_iter *i, loff_t pos)
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{
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struct address_space *mapping = file->f_mapping;
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const struct address_space_operations *a_ops = mapping->a_ops;
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struct inode *inode = mapping->host;
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long status = 0;
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ssize_t written = 0;
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do {
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struct page *src_page;
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struct page *page;
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pgoff_t index; /* Pagecache index for current page */
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unsigned long offset; /* Offset into pagecache page */
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unsigned long bytes; /* Bytes to write to page */
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size_t copied; /* Bytes copied from user */
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offset = (pos & (PAGE_CACHE_SIZE - 1));
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index = pos >> PAGE_CACHE_SHIFT;
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bytes = min_t(unsigned long, PAGE_CACHE_SIZE - offset,
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iov_iter_count(i));
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/*
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* a non-NULL src_page indicates that we're doing the
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* copy via get_user_pages and kmap.
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*/
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src_page = NULL;
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/*
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* Bring in the user page that we will copy from _first_.
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* Otherwise there's a nasty deadlock on copying from the
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* same page as we're writing to, without it being marked
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* up-to-date.
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*
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* Not only is this an optimisation, but it is also required
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* to check that the address is actually valid, when atomic
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* usercopies are used, below.
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*/
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if (unlikely(iov_iter_fault_in_readable(i, bytes))) {
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status = -EFAULT;
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break;
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}
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page = __grab_cache_page(mapping, index);
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if (!page) {
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status = -ENOMEM;
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break;
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}
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/*
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* non-uptodate pages cannot cope with short copies, and we
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* cannot take a pagefault with the destination page locked.
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* So pin the source page to copy it.
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*/
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if (!PageUptodate(page) && !segment_eq(get_fs(), KERNEL_DS)) {
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unlock_page(page);
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src_page = alloc_page(GFP_KERNEL);
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if (!src_page) {
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page_cache_release(page);
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status = -ENOMEM;
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break;
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}
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|
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/*
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* Cannot get_user_pages with a page locked for the
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* same reason as we can't take a page fault with a
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* page locked (as explained below).
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*/
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copied = iov_iter_copy_from_user(src_page, i,
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offset, bytes);
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if (unlikely(copied == 0)) {
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status = -EFAULT;
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page_cache_release(page);
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page_cache_release(src_page);
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break;
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}
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bytes = copied;
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lock_page(page);
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/*
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* Can't handle the page going uptodate here, because
|
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* that means we would use non-atomic usercopies, which
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* zero out the tail of the page, which can cause
|
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* zeroes to become transiently visible. We could just
|
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* use a non-zeroing copy, but the APIs aren't too
|
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* consistent.
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*/
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if (unlikely(!page->mapping || PageUptodate(page))) {
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unlock_page(page);
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page_cache_release(page);
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page_cache_release(src_page);
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continue;
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}
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}
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|
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status = a_ops->prepare_write(file, page, offset, offset+bytes);
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if (unlikely(status))
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goto fs_write_aop_error;
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|
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if (!src_page) {
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/*
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* Must not enter the pagefault handler here, because
|
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* we hold the page lock, so we might recursively
|
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* deadlock on the same lock, or get an ABBA deadlock
|
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* against a different lock, or against the mmap_sem
|
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* (which nests outside the page lock). So increment
|
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* preempt count, and use _atomic usercopies.
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*
|
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* The page is uptodate so we are OK to encounter a
|
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* short copy: if unmodified parts of the page are
|
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* marked dirty and written out to disk, it doesn't
|
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* really matter.
|
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*/
|
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pagefault_disable();
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copied = iov_iter_copy_from_user_atomic(page, i,
|
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offset, bytes);
|
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pagefault_enable();
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} else {
|
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void *src, *dst;
|
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src = kmap_atomic(src_page, KM_USER0);
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dst = kmap_atomic(page, KM_USER1);
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memcpy(dst + offset, src + offset, bytes);
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kunmap_atomic(dst, KM_USER1);
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kunmap_atomic(src, KM_USER0);
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copied = bytes;
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}
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flush_dcache_page(page);
|
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|
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status = a_ops->commit_write(file, page, offset, offset+bytes);
|
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if (unlikely(status < 0))
|
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goto fs_write_aop_error;
|
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if (unlikely(status > 0)) /* filesystem did partial write */
|
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copied = min_t(size_t, copied, status);
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|
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unlock_page(page);
|
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mark_page_accessed(page);
|
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page_cache_release(page);
|
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if (src_page)
|
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page_cache_release(src_page);
|
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|
||||
iov_iter_advance(i, copied);
|
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pos += copied;
|
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written += copied;
|
||||
|
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balance_dirty_pages_ratelimited(mapping);
|
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cond_resched();
|
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continue;
|
||||
|
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fs_write_aop_error:
|
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unlock_page(page);
|
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page_cache_release(page);
|
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if (src_page)
|
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page_cache_release(src_page);
|
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|
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/*
|
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* prepare_write() may have instantiated a few blocks
|
||||
* outside i_size. Trim these off again. Don't need
|
||||
* i_size_read because we hold i_mutex.
|
||||
*/
|
||||
if (pos + bytes > inode->i_size)
|
||||
vmtruncate(inode, inode->i_size);
|
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break;
|
||||
} while (iov_iter_count(i));
|
||||
|
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return written ? written : status;
|
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}
|
||||
|
||||
static ssize_t generic_perform_write(struct file *file,
|
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struct iov_iter *i, loff_t pos)
|
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{
|
||||
|
|
@ -2494,10 +2263,7 @@ generic_file_buffered_write(struct kiocb *iocb, const struct iovec *iov,
|
|||
struct iov_iter i;
|
||||
|
||||
iov_iter_init(&i, iov, nr_segs, count, written);
|
||||
if (a_ops->write_begin)
|
||||
status = generic_perform_write(file, &i, pos);
|
||||
else
|
||||
status = generic_perform_write_2copy(file, &i, pos);
|
||||
|
||||
if (likely(status >= 0)) {
|
||||
written += status;
|
||||
|
|
|
|||
Загрузка…
Ссылка в новой задаче