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Message-Id: <1222294559.6491.52.camel@badari-desktop>
Date: Wed, 24 Sep 2008 15:15:59 -0700
From: Badari Pulavarty <pbadari@...il.com>
To: Christoph Hellwig <hch@...radead.org>
Cc: Jeff Layton <jlayton@...hat.com>, smfrench@...il.com,
linux-cifs-client@...ts.samba.org, linux-fsdevel@...r.kernel.org,
linux-kernel@...r.kernel.org, npiggin@...e.de
Subject: Re: [PATCH] cifs: Convert cifs to new aops.
On Wed, 2008-09-24 at 13:54 -0400, Christoph Hellwig wrote:
> Might be worth Ccing Nick as he's started on finishing the last aops
> conversions again at Kernel Summit.
Yes. Its me, who started this again (after talking to Nick at KS) -
trying to make use ecryptfs and cifs gets converted to new aops. Nick
has been on the CCed on all our (private) mails.
BTW, I posted ecryptfs conversion also. Only thing remaining is
afs. Once thats done, we can get rid of prepare/commit write.
Thanks,
Badari
>
> On Wed, Sep 24, 2008 at 01:39:13PM -0400, Jeff Layton wrote:
> > This patch is based on the one originally posted by Nick Piggin. His
> > patch was very close, but had a couple of small bugs. Nick's original
> > comments follow:
> >
> > ---------------[snip]--------------
> >
> > This is another relatively naive conversion. Always do the read upfront
> > when the page is not uptodate (unless we're in the writethrough path).
> >
> > Fix an uninitialized data exposure where SetPageUptodate was called
> > before the page was uptodate.
> >
> > SetPageUptodate and switch to writeback mode in the case that the full
> > page was dirtied.
> >
> > Signed-off-by: Jeff Layton <jlayton@...hat.com>
> > Reviewed-by: Badari Pulavarty <pbadari@...ibm.com>
> > Acked-by: Dave Kleikamp <shaggy@...ux.vnet.ibm.com>
> > Cc: Steve French <smfrench@...il.com>
> > Cc: Nick Piggin <npiggin@...e.de>
> > ---
> > fs/cifs/file.c | 120 +++++++++++++++++++++++++++----------------------------
> > 1 files changed, 59 insertions(+), 61 deletions(-)
> >
> > diff --git a/fs/cifs/file.c b/fs/cifs/file.c
> > index d39e852..c4a8a06 100644
> > --- a/fs/cifs/file.c
> > +++ b/fs/cifs/file.c
> > @@ -107,7 +107,7 @@ static inline int cifs_open_inode_helper(struct inode *inode, struct file *file,
> >
> > /* want handles we can use to read with first
> > in the list so we do not have to walk the
> > - list to search for one in prepare_write */
> > + list to search for one in write_begin */
> > if ((file->f_flags & O_ACCMODE) == O_WRONLY) {
> > list_add_tail(&pCifsFile->flist,
> > &pCifsInode->openFileList);
> > @@ -915,7 +915,7 @@ ssize_t cifs_user_write(struct file *file, const char __user *write_data,
> > }
> >
> > static ssize_t cifs_write(struct file *file, const char *write_data,
> > - size_t write_size, loff_t *poffset)
> > + size_t write_size, loff_t *poffset)
> > {
> > int rc = 0;
> > unsigned int bytes_written = 0;
> > @@ -1455,49 +1455,52 @@ static int cifs_writepage(struct page *page, struct writeback_control *wbc)
> > return rc;
> > }
> >
> > -static int cifs_commit_write(struct file *file, struct page *page,
> > - unsigned offset, unsigned to)
> > +static int cifs_write_end(struct file *file, struct address_space *mapping,
> > + loff_t pos, unsigned len, unsigned copied,
> > + struct page *page, void *fsdata)
> > {
> > - int xid;
> > - int rc = 0;
> > - struct inode *inode = page->mapping->host;
> > - loff_t position = ((loff_t)page->index << PAGE_CACHE_SHIFT) + to;
> > - char *page_data;
> > + int rc;
> > + struct inode *inode = mapping->host;
> >
> > - xid = GetXid();
> > - cFYI(1, ("commit write for page %p up to position %lld for %d",
> > - page, position, to));
> > - spin_lock(&inode->i_lock);
> > - if (position > inode->i_size)
> > - i_size_write(inode, position);
> > + cFYI(1, ("write_end for page %p from pos %lld with %d bytes",
> > + page, pos, copied));
> > +
> > + if (!PageUptodate(page) && copied == PAGE_CACHE_SIZE)
> > + SetPageUptodate(page);
> >
> > - spin_unlock(&inode->i_lock);
> > if (!PageUptodate(page)) {
> > - position = ((loff_t)page->index << PAGE_CACHE_SHIFT) + offset;
> > - /* can not rely on (or let) writepage write this data */
> > - if (to < offset) {
> > - cFYI(1, ("Illegal offsets, can not copy from %d to %d",
> > - offset, to));
> > - FreeXid(xid);
> > - return rc;
> > - }
> > + char *page_data;
> > + unsigned offset = pos & (PAGE_CACHE_SIZE - 1);
> > + int xid;
> > +
> > + xid = GetXid();
> > /* this is probably better than directly calling
> > partialpage_write since in this function the file handle is
> > known which we might as well leverage */
> > /* BB check if anything else missing out of ppw
> > such as updating last write time */
> > page_data = kmap(page);
> > - rc = cifs_write(file, page_data + offset, to-offset,
> > - &position);
> > - if (rc > 0)
> > - rc = 0;
> > - /* else if (rc < 0) should we set writebehind rc? */
> > + rc = cifs_write(file, page_data + offset, copied, &pos);
> > + /* if (rc < 0) should we set writebehind rc? */
> > kunmap(page);
> > +
> > + FreeXid(xid);
> > } else {
> > + rc = copied;
> > + pos += copied;
> > set_page_dirty(page);
> > }
> >
> > - FreeXid(xid);
> > + if (rc > 0) {
> > + spin_lock(&inode->i_lock);
> > + if (pos > inode->i_size)
> > + i_size_write(inode, pos);
> > + spin_unlock(&inode->i_lock);
> > + }
> > +
> > + unlock_page(page);
> > + page_cache_release(page);
> > +
> > return rc;
> > }
> >
> > @@ -2043,49 +2046,44 @@ bool is_size_safe_to_change(struct cifsInodeInfo *cifsInode, __u64 end_of_file)
> > return true;
> > }
> >
> > -static int cifs_prepare_write(struct file *file, struct page *page,
> > - unsigned from, unsigned to)
> > +static int cifs_write_begin(struct file *file, struct address_space *mapping,
> > + loff_t pos, unsigned len, unsigned flags,
> > + struct page **pagep, void **fsdata)
> > {
> > - int rc = 0;
> > - loff_t i_size;
> > - loff_t offset;
> > + pgoff_t index = pos >> PAGE_CACHE_SHIFT;
> > + loff_t offset = pos & (PAGE_CACHE_SIZE - 1);
> > +
> > + cFYI(1, ("write_begin from %lld len %d", (long long)pos, len));
> > +
> > + *pagep = __grab_cache_page(mapping, index);
> > + if (!*pagep)
> > + return -ENOMEM;
> >
> > - cFYI(1, ("prepare write for page %p from %d to %d", page, from, to));
> > - if (PageUptodate(page))
> > + if (PageUptodate(*pagep))
> > return 0;
> >
> > /* If we are writing a full page it will be up to date,
> > no need to read from the server */
> > - if ((to == PAGE_CACHE_SIZE) && (from == 0)) {
> > - SetPageUptodate(page);
> > + if (len == PAGE_CACHE_SIZE && flags & AOP_FLAG_UNINTERRUPTIBLE)
> > return 0;
> > - }
> >
> > - offset = (loff_t)page->index << PAGE_CACHE_SHIFT;
> > - i_size = i_size_read(page->mapping->host);
> > + if ((file->f_flags & O_ACCMODE) != O_WRONLY) {
> > + int rc;
> >
> > - if ((offset >= i_size) ||
> > - ((from == 0) && (offset + to) >= i_size)) {
> > - /*
> > - * We don't need to read data beyond the end of the file.
> > - * zero it, and set the page uptodate
> > - */
> > - simple_prepare_write(file, page, from, to);
> > - SetPageUptodate(page);
> > - } else if ((file->f_flags & O_ACCMODE) != O_WRONLY) {
> > /* might as well read a page, it is fast enough */
> > - rc = cifs_readpage_worker(file, page, &offset);
> > + rc = cifs_readpage_worker(file, *pagep, &offset);
> > +
> > + /* we do not need to pass errors back
> > + e.g. if we do not have read access to the file
> > + because cifs_write_end will attempt synchronous writes
> > + -- shaggy */
> > } else {
> > /* we could try using another file handle if there is one -
> > but how would we lock it to prevent close of that handle
> > racing with this read? In any case
> > - this will be written out by commit_write so is fine */
> > + this will be written out by write_end so is fine */
> > }
> >
> > - /* we do not need to pass errors back
> > - e.g. if we do not have read access to the file
> > - because cifs_commit_write will do the right thing. -- shaggy */
> > -
> > return 0;
> > }
> >
> > @@ -2094,8 +2092,8 @@ const struct address_space_operations cifs_addr_ops = {
> > .readpages = cifs_readpages,
> > .writepage = cifs_writepage,
> > .writepages = cifs_writepages,
> > - .prepare_write = cifs_prepare_write,
> > - .commit_write = cifs_commit_write,
> > + .write_begin = cifs_write_begin,
> > + .write_end = cifs_write_end,
> > .set_page_dirty = __set_page_dirty_nobuffers,
> > /* .sync_page = cifs_sync_page, */
> > /* .direct_IO = */
> > @@ -2110,8 +2108,8 @@ const struct address_space_operations cifs_addr_ops_smallbuf = {
> > .readpage = cifs_readpage,
> > .writepage = cifs_writepage,
> > .writepages = cifs_writepages,
> > - .prepare_write = cifs_prepare_write,
> > - .commit_write = cifs_commit_write,
> > + .write_begin = cifs_write_begin,
> > + .write_end = cifs_write_end,
> > .set_page_dirty = __set_page_dirty_nobuffers,
> > /* .sync_page = cifs_sync_page, */
> > /* .direct_IO = */
> > --
> > 1.5.5.1
> >
> > --
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