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dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=Content-Transfer-Encoding:MIME-Version: References:In-Reply-To:Message-ID:Date:Subject:Cc:To:From:Sender:Reply-To: Content-Type:Content-ID:Content-Description; bh=rNhqStnPi0LQIT1jWD+BHswn8m4DZffZMrQiTgaOunA=; b=e+/iCc0QLvuuxR+UQ68sbys9bL NnFieCYhYgcNRXIZz0irZsz7essAW2lr6Nfu7LGTxabfQB0gDN/2jzaJQnIOhxBOKMZkXQJ67VOtI E0teEhPWNoz92oKsv4fi6rNe3n+HrwDaf1XQ6fmggrPVjVPT3b4poMAZAxABHkjSzlIrFJVQWwini +t0jVAAUS1Qm0cw7tP0r1PQYiLohUywQJMSP7rdUv80LWRfb9Qx5kn07jG7qQcWHsaNHW0DNb4khh 3UZCS6nrY8WC5FvpPwweJ8bHtueHssBwFikQ81olBEgX29x9EW2eoN/qvvPi8I8KMmLTM/9EaI7uU czTj4LOg==; Received: from willy by casper.infradead.org with local (Exim 4.97.1 #2 (Red Hat Linux)) id 1sBzzz-00000008pj3-0mih; Tue, 28 May 2024 16:48:31 +0000 From: "Matthew Wilcox (Oracle)" To: Christoph Hellwig Cc: "Matthew Wilcox (Oracle)" , linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org Subject: [PATCH 1/7] fs: Introduce buffered_write_operations Date: Tue, 28 May 2024 17:48:22 +0100 Message-ID: <20240528164829.2105447-2-willy@infradead.org> X-Mailer: git-send-email 2.44.0 In-Reply-To: <20240528164829.2105447-1-willy@infradead.org> References: <20240528164829.2105447-1-willy@infradead.org> Precedence: bulk X-Mailing-List: linux-ext4@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Start the process of moving write_begin and write_end out from the address_space_operations to their own struct. The new write_begin returns the folio or an ERR_PTR instead of returning the folio by reference. It also accepts len as a size_t and (as documented) the len may be larger than PAGE_SIZE. Pass an optional buffered_write_operations pointer to various functions in filemap.c. The old names are available as macros for now, except for generic_file_write_iter() which is used as a function pointer by many filesystems. If using the new functions, the filesystem can have per-operation fsdata instead of per-page fsdata. Signed-off-by: Matthew Wilcox (Oracle) --- Documentation/filesystems/locking.rst | 23 ++++++++ fs/jfs/file.c | 3 +- fs/ramfs/file-mmu.c | 3 +- fs/ufs/file.c | 2 +- include/linux/fs.h | 3 -- include/linux/pagemap.h | 21 ++++++++ mm/filemap.c | 77 +++++++++++++++++---------- 7 files changed, 97 insertions(+), 35 deletions(-) diff --git a/Documentation/filesystems/locking.rst b/Documentation/filesystems/locking.rst index e664061ed55d..e62a8a83ea9e 100644 --- a/Documentation/filesystems/locking.rst +++ b/Documentation/filesystems/locking.rst @@ -413,6 +413,29 @@ path after ->swap_activate() returned success. ->swap_rw will be called for swap IO if SWP_FS_OPS was set by ->swap_activate(). +buffered_write_operations +========================= + + struct folio *(*write_begin)(struct file *, struct address_space *, + loff_t pos, size_t len, void **fsdata); + size_t (*write_end)(struct file *, struct address_space *, + loff_t pos, size_t len, size_t copied, + struct folio *folio, void **fsdata); + +For write_begin, 'len' is typically the remaining length of the write, +and is not capped to PAGE_SIZE. For write_end, len will be limited so +that pos + len <= folio_pos(folio) + folio_size(folio). copied will +not exceed len. pos + len will not exceed MAX_LFS_FILESIZE. + +write_begin may return an ERR_PTR. write_end may return a number less +than copied if it needs the caller to retry from an earlier position in +the file. It cannot signal an error; that must be done by write_begin(). + +write_begin should lock the folio and increase its refcount. write_end +should unlock it and drop the refcount, possibly after setting it +uptodate (it can only use folio_end_read() for this if it knows the folio +was not previously uptodate; probably best not to use it). + file_lock_operations ==================== diff --git a/fs/jfs/file.c b/fs/jfs/file.c index 01b6912e60f8..9c62445ea6be 100644 --- a/fs/jfs/file.c +++ b/fs/jfs/file.c @@ -4,8 +4,7 @@ * Portions Copyright (C) Christoph Hellwig, 2001-2002 */ -#include -#include +#include #include #include #include "jfs_incore.h" diff --git a/fs/ramfs/file-mmu.c b/fs/ramfs/file-mmu.c index b45c7edc3225..5de2a232d07f 100644 --- a/fs/ramfs/file-mmu.c +++ b/fs/ramfs/file-mmu.c @@ -24,8 +24,7 @@ * caches is sufficient. */ -#include -#include +#include #include #include diff --git a/fs/ufs/file.c b/fs/ufs/file.c index 6558882a89ef..b557d4a14143 100644 --- a/fs/ufs/file.c +++ b/fs/ufs/file.c @@ -24,7 +24,7 @@ * ext2 fs regular file handling primitives */ -#include +#include #include "ufs_fs.h" #include "ufs.h" diff --git a/include/linux/fs.h b/include/linux/fs.h index 0283cf366c2a..4c6c2042cbeb 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -3115,10 +3115,7 @@ extern int generic_file_rw_checks(struct file *file_in, struct file *file_out); ssize_t filemap_read(struct kiocb *iocb, struct iov_iter *to, ssize_t already_read); extern ssize_t generic_file_read_iter(struct kiocb *, struct iov_iter *); -extern ssize_t __generic_file_write_iter(struct kiocb *, struct iov_iter *); -extern ssize_t generic_file_write_iter(struct kiocb *, struct iov_iter *); extern ssize_t generic_file_direct_write(struct kiocb *, struct iov_iter *); -ssize_t generic_perform_write(struct kiocb *, struct iov_iter *); ssize_t direct_write_fallback(struct kiocb *iocb, struct iov_iter *iter, ssize_t direct_written, ssize_t buffered_written); diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h index ee633712bba0..2921c1cc6335 100644 --- a/include/linux/pagemap.h +++ b/include/linux/pagemap.h @@ -18,6 +18,27 @@ struct folio_batch; +struct buffered_write_operations { + struct folio *(*write_begin)(struct file *, struct address_space *, + loff_t pos, size_t len, void **fsdata); + size_t (*write_end)(struct file *, struct address_space *, + loff_t pos, size_t len, size_t copied, + struct folio *folio, void **fsdata); +}; + +ssize_t filemap_write_iter(struct kiocb *, struct iov_iter *, + const struct buffered_write_operations *, void *fsdata); +ssize_t __filemap_write_iter(struct kiocb *, struct iov_iter *, + const struct buffered_write_operations *, void *fsdata); +ssize_t filemap_perform_write(struct kiocb *, struct iov_iter *, + const struct buffered_write_operations *, void *fsdata); + +ssize_t generic_file_write_iter(struct kiocb *, struct iov_iter *); +#define generic_perform_write(kiocb, iter) \ + filemap_perform_write(kiocb, iter, NULL, NULL) +#define __generic_file_write_iter(kiocb, iter) \ + __filemap_write_iter(kiocb, iter, NULL, NULL) + unsigned long invalidate_mapping_pages(struct address_space *mapping, pgoff_t start, pgoff_t end); diff --git a/mm/filemap.c b/mm/filemap.c index 382c3d06bfb1..162ac110c423 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -95,7 +95,7 @@ * ->invalidate_lock (filemap_fault) * ->lock_page (filemap_fault, access_process_vm) * - * ->i_rwsem (generic_perform_write) + * ->i_rwsem (filemap_perform_write) * ->mmap_lock (fault_in_readable->do_page_fault) * * bdi->wb.list_lock @@ -3975,7 +3975,8 @@ generic_file_direct_write(struct kiocb *iocb, struct iov_iter *from) } EXPORT_SYMBOL(generic_file_direct_write); -ssize_t generic_perform_write(struct kiocb *iocb, struct iov_iter *i) +ssize_t filemap_perform_write(struct kiocb *iocb, struct iov_iter *i, + const struct buffered_write_operations *ops, void *fsdata) { struct file *file = iocb->ki_filp; loff_t pos = iocb->ki_pos; @@ -3985,11 +3986,10 @@ ssize_t generic_perform_write(struct kiocb *iocb, struct iov_iter *i) ssize_t written = 0; do { - struct page *page; - unsigned long offset; /* Offset into pagecache page */ - unsigned long bytes; /* Bytes to write to page */ + struct folio *folio; + size_t offset; /* Offset into pagecache folio */ + size_t bytes; /* Bytes to write to page */ size_t copied; /* Bytes copied from user */ - void *fsdata = NULL; offset = (pos & (PAGE_SIZE - 1)); bytes = min_t(unsigned long, PAGE_SIZE - offset, @@ -4012,19 +4012,33 @@ ssize_t generic_perform_write(struct kiocb *iocb, struct iov_iter *i) break; } - status = a_ops->write_begin(file, mapping, pos, bytes, + if (ops) { + folio = ops->write_begin(file, mapping, pos, bytes, &fsdata); + if (IS_ERR(folio)) { + status = PTR_ERR(folio); + break; + } + } else { + struct page *page; + status = a_ops->write_begin(file, mapping, pos, bytes, &page, &fsdata); - if (unlikely(status < 0)) - break; + if (unlikely(status < 0)) + break; + folio = page_folio(page); + } if (mapping_writably_mapped(mapping)) - flush_dcache_page(page); + flush_dcache_folio(folio); - copied = copy_page_from_iter_atomic(page, offset, bytes, i); - flush_dcache_page(page); + copied = copy_folio_from_iter_atomic(folio, offset, bytes, i); + flush_dcache_folio(folio); - status = a_ops->write_end(file, mapping, pos, bytes, copied, - page, fsdata); + if (ops) + status = ops->write_end(file, mapping, pos, bytes, + copied, folio, &fsdata); + else + status = a_ops->write_end(file, mapping, pos, bytes, + copied, &folio->page, fsdata); if (unlikely(status != copied)) { iov_iter_revert(i, copied - max(status, 0L)); if (unlikely(status < 0)) @@ -4054,12 +4068,13 @@ ssize_t generic_perform_write(struct kiocb *iocb, struct iov_iter *i) iocb->ki_pos += written; return written; } -EXPORT_SYMBOL(generic_perform_write); +EXPORT_SYMBOL(filemap_perform_write); /** - * __generic_file_write_iter - write data to a file - * @iocb: IO state structure (file, offset, etc.) - * @from: iov_iter with data to write + * __filemap_write_iter - write data to a file + * @iocb: IO state structure (file, offset, etc.) + * @from: iov_iter with data to write + * @ops: How to inform the filesystem that a write is starting/finishing. * * This function does all the work needed for actually writing data to a * file. It does all basic checks, removes SUID from the file, updates @@ -4077,7 +4092,8 @@ EXPORT_SYMBOL(generic_perform_write); * * number of bytes written, even for truncated writes * * negative error code if no data has been written at all */ -ssize_t __generic_file_write_iter(struct kiocb *iocb, struct iov_iter *from) +ssize_t __filemap_write_iter(struct kiocb *iocb, struct iov_iter *from, + const struct buffered_write_operations *ops, void *fsdata) { struct file *file = iocb->ki_filp; struct address_space *mapping = file->f_mapping; @@ -4104,27 +4120,29 @@ ssize_t __generic_file_write_iter(struct kiocb *iocb, struct iov_iter *from) if (ret < 0 || !iov_iter_count(from) || IS_DAX(inode)) return ret; return direct_write_fallback(iocb, from, ret, - generic_perform_write(iocb, from)); + filemap_perform_write(iocb, from, ops, fsdata)); } - return generic_perform_write(iocb, from); + return filemap_perform_write(iocb, from, ops, fsdata); } -EXPORT_SYMBOL(__generic_file_write_iter); +EXPORT_SYMBOL(__filemap_write_iter); /** - * generic_file_write_iter - write data to a file + * filemap_write_iter - write data to a file * @iocb: IO state structure * @from: iov_iter with data to write * - * This is a wrapper around __generic_file_write_iter() to be used by most + * This is a wrapper around __filemap_write_iter() to be used by most * filesystems. It takes care of syncing the file in case of O_SYNC file * and acquires i_rwsem as needed. + * * Return: - * * negative error code if no data has been written at all of + * * negative error code if no data has been written at all or if * vfs_fsync_range() failed for a synchronous write * * number of bytes written, even for truncated writes */ -ssize_t generic_file_write_iter(struct kiocb *iocb, struct iov_iter *from) +ssize_t filemap_write_iter(struct kiocb *iocb, struct iov_iter *from, + const struct buffered_write_operations *ops, void *fsdata) { struct file *file = iocb->ki_filp; struct inode *inode = file->f_mapping->host; @@ -4133,13 +4151,18 @@ ssize_t generic_file_write_iter(struct kiocb *iocb, struct iov_iter *from) inode_lock(inode); ret = generic_write_checks(iocb, from); if (ret > 0) - ret = __generic_file_write_iter(iocb, from); + ret = __filemap_write_iter(iocb, from, ops, fsdata); inode_unlock(inode); if (ret > 0) ret = generic_write_sync(iocb, ret); return ret; } + +ssize_t generic_file_write_iter(struct kiocb *iocb, struct iov_iter *from) +{ + return filemap_write_iter(iocb, from, NULL, NULL); +} EXPORT_SYMBOL(generic_file_write_iter); /**