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Registered in England and Wales under Company Registration No. 3798903 From: David Howells Subject: [PATCH 17/37] CacheFiles: Add a hook to write a single page of data to an inode To: Trond.Myklebust@netapp.com, chuck.lever@oracle.com, casey@schaufler-ca.com Cc: nfsv4@linux-nfs.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, selinux@tycho.nsa.gov, linux-security-module@vger.kernel.org, dhowells@redhat.com Date: Wed, 20 Feb 2008 16:07:29 +0000 Message-ID: <20080220160729.4715.28442.stgit@warthog.procyon.org.uk> In-Reply-To: <20080220160557.4715.66608.stgit@warthog.procyon.org.uk> References: <20080220160557.4715.66608.stgit@warthog.procyon.org.uk> User-Agent: StGIT/0.14.1 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6258 Lines: 174 Add an address space operation to write one single page of data to an inode at a page-aligned location (thus permitting the implementation to be highly optimised). The data source is a single page. This is used by CacheFiles to store the contents of netfs pages into their backing file pages. Supply a generic implementation for this that uses the write_begin() and write_end() address_space operations to bind a copy directly into the page cache. Hook the Ext2 and Ext3 operations to the generic implementation. Signed-off-by: David Howells --- fs/ext2/inode.c | 2 ++ fs/ext3/inode.c | 3 +++ include/linux/fs.h | 7 ++++++ mm/filemap.c | 61 ++++++++++++++++++++++++++++++++++++++++++++++++++++ 4 files changed, 73 insertions(+), 0 deletions(-) diff --git a/fs/ext2/inode.c b/fs/ext2/inode.c index c620068..f483014 100644 --- a/fs/ext2/inode.c +++ b/fs/ext2/inode.c @@ -792,6 +792,7 @@ const struct address_space_operations ext2_aops = { .direct_IO = ext2_direct_IO, .writepages = ext2_writepages, .migratepage = buffer_migrate_page, + .write_one_page = generic_file_buffered_write_one_page, }; const struct address_space_operations ext2_aops_xip = { @@ -810,6 +811,7 @@ const struct address_space_operations ext2_nobh_aops = { .direct_IO = ext2_direct_IO, .writepages = ext2_writepages, .migratepage = buffer_migrate_page, + .write_one_page = generic_file_buffered_write_one_page, }; /* diff --git a/fs/ext3/inode.c b/fs/ext3/inode.c index c976123..0209f3b 100644 --- a/fs/ext3/inode.c +++ b/fs/ext3/inode.c @@ -1776,6 +1776,7 @@ static const struct address_space_operations ext3_ordered_aops = { .releasepage = ext3_releasepage, .direct_IO = ext3_direct_IO, .migratepage = buffer_migrate_page, + .write_one_page = generic_file_buffered_write_one_page, }; static const struct address_space_operations ext3_writeback_aops = { @@ -1790,6 +1791,7 @@ static const struct address_space_operations ext3_writeback_aops = { .releasepage = ext3_releasepage, .direct_IO = ext3_direct_IO, .migratepage = buffer_migrate_page, + .write_one_page = generic_file_buffered_write_one_page, }; static const struct address_space_operations ext3_journalled_aops = { @@ -1803,6 +1805,7 @@ static const struct address_space_operations ext3_journalled_aops = { .bmap = ext3_bmap, .invalidatepage = ext3_invalidatepage, .releasepage = ext3_releasepage, + .write_one_page = generic_file_buffered_write_one_page, }; void ext3_set_aops(struct inode *inode) diff --git a/include/linux/fs.h b/include/linux/fs.h index d218ef5..dd6c3d1 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -481,6 +481,11 @@ struct address_space_operations { int (*migratepage) (struct address_space *, struct page *, struct page *); int (*launder_page) (struct page *); + /* write the contents of the source page over the page at the specified + * index in the target address space (the source page does not need to + * be related to the target address space) */ + int (*write_one_page)(struct address_space *, pgoff_t, struct page *); + }; /* @@ -1811,6 +1816,8 @@ extern ssize_t generic_file_direct_write(struct kiocb *, const struct iovec *, unsigned long *, loff_t, loff_t *, size_t, size_t); extern ssize_t generic_file_buffered_write(struct kiocb *, const struct iovec *, unsigned long, loff_t, loff_t *, size_t, ssize_t); +extern int generic_file_buffered_write_one_page(struct address_space *, + pgoff_t, struct page *); extern ssize_t do_sync_read(struct file *filp, char __user *buf, size_t len, loff_t *ppos); extern ssize_t do_sync_write(struct file *filp, const char __user *buf, size_t len, loff_t *ppos); extern int generic_segment_checks(const struct iovec *iov, diff --git a/mm/filemap.c b/mm/filemap.c index df1e149..a583f44 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -2359,6 +2359,67 @@ generic_file_buffered_write(struct kiocb *iocb, const struct iovec *iov, } EXPORT_SYMBOL(generic_file_buffered_write); +/** + * generic_file_buffered_write_one_page - Write a single page of data to an + * inode + * @mapping - The address space of the target inode + * @index - The target page in the target inode to fill + * @source - The data to write into the target page + * + * Write the data from the source page to the page in the nominated address + * space at the @index specified. Note that the file will not be extended if + * the page crosses the EOF marker, in which case only the first part of the + * page will be written. + * + * The @source page does not need to have any association with the file or the + * target page offset. + */ +int generic_file_buffered_write_one_page(struct address_space *mapping, + pgoff_t index, + struct page *source) +{ + const struct address_space_operations *a_ops = mapping->a_ops; + struct page *page; + unsigned len; + loff_t isize, pos; + void *fsdata; + int ret; + + pos = index; + pos <<= PAGE_CACHE_SHIFT; + + len = PAGE_CACHE_SIZE; + isize = i_size_read(mapping->host); + if ((isize >> PAGE_CACHE_SHIFT) == index) + len = isize & (PAGE_CACHE_SIZE - 1); + + ret = pagecache_write_begin(NULL, mapping, pos, len, + AOP_FLAG_UNINTERRUPTIBLE, &page, &fsdata); + if (ret < 0) + goto sync; + + copy_highpage(page, source); + + ret = pagecache_write_end(NULL, mapping, pos, len, len, page, fsdata); + if (ret < 0) + goto sync; + + balance_dirty_pages_ratelimited(mapping); + cond_resched(); + +sync: + /* the caller must handle O_SYNC themselves, but we handle S_SYNC and + * MS_SYNCHRONOUS here */ + if (unlikely(IS_SYNC(mapping->host)) && !a_ops->writepage) + ret = generic_osync_inode(mapping->host, mapping, + OSYNC_METADATA | OSYNC_DATA); + + /* the caller must handle O_DIRECT for themselves */ + + return ret; +} +EXPORT_SYMBOL(generic_file_buffered_write_one_page); + static ssize_t __generic_file_aio_write_nolock(struct kiocb *iocb, const struct iovec *iov, unsigned long nr_segs, loff_t *ppos) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/