diff options
| -rw-r--r-- | Documentation/filesystems/Locking | 12 | ||||
| -rw-r--r-- | Documentation/filesystems/vfs.txt | 39 | ||||
| -rw-r--r-- | drivers/block/loop.c | 5 | ||||
| -rw-r--r-- | fs/fat/inode.c | 2 | ||||
| -rw-r--r-- | fs/libfs.c | 2 | ||||
| -rw-r--r-- | fs/ocfs2/file.c | 3 | ||||
| -rw-r--r-- | fs/splice.c | 4 | ||||
| -rw-r--r-- | include/linux/fs.h | 7 | ||||
| -rw-r--r-- | mm/filemap.c | 242 |
9 files changed, 23 insertions, 293 deletions
diff --git a/Documentation/filesystems/Locking b/Documentation/filesystems/Locking index 8362860..23d2f44 100644 --- a/Documentation/filesystems/Locking +++ b/Documentation/filesystems/Locking @@ -161,8 +161,12 @@ prototypes: int (*set_page_dirty)(struct page *page); int (*readpages)(struct file *filp, struct address_space *mapping, struct list_head *pages, unsigned nr_pages); - int (*prepare_write)(struct file *, struct page *, unsigned, unsigned); - int (*commit_write)(struct file *, struct page *, unsigned, unsigned); + int (*write_begin)(struct file *, struct address_space *mapping, + loff_t pos, unsigned len, unsigned flags, + struct page **pagep, void **fsdata); + int (*write_end)(struct file *, struct address_space *mapping, + loff_t pos, unsigned len, unsigned copied, + struct page *page, void *fsdata); sector_t (*bmap)(struct address_space *, sector_t); int (*invalidatepage) (struct page *, unsigned long); int (*releasepage) (struct page *, int); @@ -180,8 +184,6 @@ sync_page: no maybe writepages: no set_page_dirty no no readpages: no -prepare_write: no yes yes -commit_write: no yes yes write_begin: no locks the page yes write_end: no yes, unlocks yes perform_write: no n/a yes @@ -191,7 +193,7 @@ releasepage: no yes direct_IO: no launder_page: no yes - ->prepare_write(), ->commit_write(), ->sync_page() and ->readpage() + ->write_begin(), ->write_end(), ->sync_page() and ->readpage() may be called from the request handler (/dev/loop). ->readpage() unlocks the page, either synchronously or via I/O diff --git a/Documentation/filesystems/vfs.txt b/Documentation/filesystems/vfs.txt index c4d348d..5579bda 100644 --- a/Documentation/filesystems/vfs.txt +++ b/Documentation/filesystems/vfs.txt @@ -492,7 +492,7 @@ written-back to storage typically in whole pages, however the address_space has finer control of write sizes. The read process essentially only requires 'readpage'. The write -process is more complicated and uses prepare_write/commit_write or +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. @@ -521,8 +521,6 @@ struct address_space_operations { int (*set_page_dirty)(struct page *page); int (*readpages)(struct file *filp, struct address_space *mapping, struct list_head *pages, unsigned nr_pages); - int (*prepare_write)(struct file *, struct page *, unsigned, unsigned); - int (*commit_write)(struct file *, struct page *, unsigned, unsigned); int (*write_begin)(struct file *, struct address_space *mapping, loff_t pos, unsigned len, unsigned flags, struct page **pagep, void **fsdata); @@ -598,37 +596,7 @@ struct address_space_operations { readpages is only used for read-ahead, so read errors are ignored. If anything goes wrong, feel free to give up. - prepare_write: called by the generic write path in VM to set up a write - request for a page. This indicates to the address space that - the given range of bytes is about to be written. The - address_space should check that the write will be able to - complete, by allocating space if necessary and doing any other - internal housekeeping. If the write will update parts of - any basic-blocks on storage, then those blocks should be - pre-read (if they haven't been read already) so that the - updated blocks can be written out properly. - The page will be locked. - - Note: the page _must not_ be marked uptodate in this function - (or anywhere else) unless it actually is uptodate right now. As - soon as a page is marked uptodate, it is possible for a concurrent - read(2) to copy it to userspace. - - commit_write: If prepare_write succeeds, new data will be copied - into the page and then commit_write will be called. It will - typically update the size of the file (if appropriate) and - mark the inode as dirty, and do any other related housekeeping - operations. It should avoid returning an error if possible - - errors should have been handled by prepare_write. - - write_begin: This is intended as a replacement for prepare_write. The - key differences being that: - - it returns a locked page (in *pagep) rather than being - given a pre locked page; - - it must be able to cope with short writes (where the - length passed to write_begin is greater than the number - of bytes copied into the page). - + write_begin: Called by the generic buffered write code to ask the filesystem to prepare to write len bytes at the given offset in the file. The address_space should check that the write will be able to complete, @@ -640,6 +608,9 @@ struct address_space_operations { The filesystem must return the locked pagecache page for the specified offset, in *pagep, for the caller to write into. + It must be able to cope with short writes (where the length passed to + write_begin is greater than the number of bytes copied into the page). + flags is a field for AOP_FLAG_xxx flags, described in include/linux/fs.h. diff --git a/drivers/block/loop.c b/drivers/block/loop.c index 3f09cd8..5c4ee70 100644 --- a/drivers/block/loop.c +++ b/drivers/block/loop.c @@ -40,8 +40,7 @@ * Heinz Mauelshagen <mge@sistina.com>, Feb 2002 * * Support for falling back on the write file operation when the address space - * operations prepare_write and/or commit_write are not available on the - * backing filesystem. + * operations write_begin is not available on the backing filesystem. * Anton Altaparmakov, 16 Feb 2005 * * Still To Fix: @@ -765,7 +764,7 @@ static int loop_set_fd(struct loop_device *lo, fmode_t mode, */ if (!file->f_op->splice_read) goto out_putf; - if (aops->prepare_write || aops->write_begin) + if (aops->write_begin) lo_flags |= LO_FLAGS_USE_AOPS; if (!(lo_flags & LO_FLAGS_USE_AOPS) && !file->f_op->write) lo_flags |= LO_FLAGS_READ_ONLY; diff --git a/fs/fat/inode.c b/fs/fat/inode.c index 19eafbe..2b2eec1 100644 --- a/fs/fat/inode.c +++ b/fs/fat/inode.c @@ -175,7 +175,7 @@ static ssize_t fat_direct_IO(int rw, struct kiocb *iocb, if (rw == WRITE) { /* - * FIXME: blockdev_direct_IO() doesn't use ->prepare_write(), + * FIXME: blockdev_direct_IO() doesn't use ->write_begin(), * so we need to update the ->mmu_private to block boundary. * * But we must fill the remaining area or hole by nul for @@ -814,7 +814,7 @@ EXPORT_SYMBOL(simple_getattr); EXPORT_SYMBOL(simple_link); EXPORT_SYMBOL(simple_lookup); EXPORT_SYMBOL(simple_pin_fs); -EXPORT_SYMBOL(simple_prepare_write); +EXPORT_UNUSED_SYMBOL(simple_prepare_write); EXPORT_SYMBOL(simple_readpage); EXPORT_SYMBOL(simple_release_fs); EXPORT_SYMBOL(simple_rename); diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c index 8d3225a..7efe937 100644 --- a/fs/ocfs2/file.c +++ b/fs/ocfs2/file.c @@ -679,8 +679,7 @@ leave: /* Some parts of this taken from generic_cont_expand, which turned out * to be too fragile to do exactly what we need without us having to - * worry about recursive locking in ->prepare_write() and - * ->commit_write(). */ + * worry about recursive locking in ->write_begin() and ->write_end(). */ static int ocfs2_write_zero_page(struct inode *inode, u64 size) { diff --git a/fs/splice.c b/fs/splice.c index a1e701c..1abab5c 100644 --- a/fs/splice.c +++ b/fs/splice.c @@ -731,8 +731,8 @@ ssize_t splice_from_pipe(struct pipe_inode_info *pipe, struct file *out, }; /* - * The actor worker might be calling ->prepare_write and - * ->commit_write. Most of the time, these expect i_mutex to + * The actor worker might be calling ->write_begin and + * ->write_end. Most of the time, these expect i_mutex to * be held. Since this may result in an ABBA deadlock with * pipe->inode, we have to order lock acquiry here. */ diff --git a/include/linux/fs.h b/include/linux/fs.h index 5b248d6..0dcdd94 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -489,13 +489,6 @@ struct address_space_operations { int (*readpages)(struct file *filp, struct address_space *mapping, struct list_head *pages, unsigned nr_pages); - /* - * ext3 requires that a successful prepare_write() call be followed - * by a commit_write() call - they must be balanced - */ - int (*prepare_write)(struct file *, struct page *, unsigned, unsigned); - int (*commit_write)(struct file *, struct page *, unsigned, unsigned); - int (*write_begin)(struct file *, struct address_space *mapping, loff_t pos, unsigned len, unsigned flags, struct page **pagep, void **fsdata); diff --git a/mm/filemap.c b/mm/filemap.c index ab85536..f3e5f89 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -2029,48 +2029,8 @@ int pagecache_write_begin(struct file *file, struct address_space *mapping, { const struct address_space_operations *aops = mapping->a_ops; - if (aops->write_begin) { - return aops->write_begin(file, mapping, pos, len, flags, + return aops->write_begin(file, mapping, pos, len, flags, pagep, fsdata); - } else { - int ret; - pgoff_t index = pos >> PAGE_CACHE_SHIFT; - unsigned offset = pos & (PAGE_CACHE_SIZE - 1); - struct inode *inode = mapping->host; - struct page *page; -again: - page = __grab_cache_page(mapping, index); - *pagep = page; - if (!page) - return -ENOMEM; - - if (flags & AOP_FLAG_UNINTERRUPTIBLE && !PageUptodate(page)) { - /* - * There is no way to resolve a short write situation - * for a !Uptodate page (except by double copying in - * the caller done by generic_perform_write_2copy). - * - * Instead, we have to bring it uptodate here. - */ - ret = aops->readpage(file, page); - page_cache_release(page); - if (ret) { - if (ret == AOP_TRUNCATED_PAGE) - goto again; - return ret; - } - goto again; - } - - ret = aops->prepare_write(file, page, offset, offset+len); - if (ret) { - unlock_page(page); - page_cache_release(page); - if (pos + len > inode->i_size) - vmtruncate(inode, inode->i_size); - } - return ret; - } } EXPORT_SYMBOL(pagecache_write_begin); @@ -2079,32 +2039,9 @@ int pagecache_write_end(struct file *file, struct address_space *mapping, struct page *page, void *fsdata) { const struct address_space_operations *aops = mapping->a_ops; - int ret; - - if (aops->write_end) { - mark_page_accessed(page); - ret = aops->write_end(file, mapping, pos, len, copied, - page, fsdata); - } else { - unsigned offset = pos & (PAGE_CACHE_SIZE - 1); - struct inode *inode = mapping->host; - - flush_dcache_page(page); - ret = aops->commit_write(file, page, offset, offset+len); - unlock_page(page); - mark_page_accessed(page); - page_cache_release(page); - - if (ret < 0) { - if (pos + len > inode->i_size) - vmtruncate(inode, inode->i_size); - } else if (ret > 0) - ret = min_t(size_t, copied, ret); - else - ret = copied; - } - return ret; + mark_page_accessed(page); + return aops->write_end(file, mapping, pos, len, copied, page, fsdata); } EXPORT_SYMBOL(pagecache_write_end); @@ -2226,174 +2163,6 @@ repeat: } EXPORT_SYMBOL(__grab_cache_page); -static ssize_t generic_perform_write_2copy(struct file *file, - struct iov_iter *i, loff_t pos) -{ - struct address_space *mapping = file->f_mapping; - const struct address_space_operations *a_ops = mapping->a_ops; - struct inode *inode = mapping->host; - long status = 0; - ssize_t written = 0; - - do { - struct page *src_page; - struct page *page; - pgoff_t index; /* Pagecache index for current page */ - unsigned long offset; /* Offset into pagecache page */ - unsigned long bytes; /* Bytes to write to page */ - size_t copied; /* Bytes copied from user */ - - offset = (pos & (PAGE_CACHE_SIZE - 1)); - index = pos >> PAGE_CACHE_SHIFT; - bytes = min_t(unsigned long, PAGE_CACHE_SIZE - offset, - iov_iter_count(i)); - - /* - * a non-NULL src_page indicates that we're doing the - * copy via get_user_pages and kmap. - */ - src_page = NULL; - - /* - * Bring in the user page that we will copy from _first_. - * Otherwise there's a nasty deadlock on copying from the - * same page as we're writing to, without it being marked - * up-to-date. - * - * Not only is this an optimisation, but it is also required - * to check that the address is actually valid, when atomic - * usercopies are used, below. - */ - if (unlikely(iov_iter_fault_in_readable(i, bytes))) { - status = -EFAULT; - break; - } - - page = __grab_cache_page(mapping, index); - if (!page) { - status = -ENOMEM; - break; - } - - /* - * non-uptodate pages cannot cope with short copies, and we - * cannot take a pagefault with the destination page locked. - * So pin the source page to copy it. - */ - if (!PageUptodate(page) && !segment_eq(get_fs(), KERNEL_DS)) { - unlock_page(page); - - src_page = alloc_page(GFP_KERNEL); - if (!src_page) { - page_cache_release(page); - status = -ENOMEM; - break; - } - - /* - * Cannot get_user_pages with a page locked for the - * same reason as we can't take a page fault with a - * page locked (as explained below). - */ - copied = iov_iter_copy_from_user(src_page, i, - offset, bytes); - if (unlikely(copied == 0)) { - status = -EFAULT; - page_cache_release(page); - page_cache_release(src_page); - break; - } - bytes = copied; - - lock_page(page); - /* - * Can't handle the page going uptodate here, because - * that means we would use non-atomic usercopies, which - * zero out the tail of the page, which can cause - * zeroes to become transiently visible. We could just - * use a non-zeroing copy, but the APIs aren't too - * consistent. - */ - if (unlikely(!page->mapping || PageUptodate(page))) { - unlock_page(page); - page_cache_release(page); - page_cache_release(src_page); - continue; - } - } - - status = a_ops->prepare_write(file, page, offset, offset+bytes); - if (unlikely(status)) - goto fs_write_aop_error; - - if (!src_page) { - /* - * Must not enter the pagefault handler here, because - * we hold the page lock, so we might recursively - * deadlock on the same lock, or get an ABBA deadlock - * against a different lock, or against the mmap_sem - * (which nests outside the page lock). So increment - * preempt count, and use _atomic usercopies. - * - * The page is uptodate so we are OK to encounter a - * short copy: if unmodified parts of the page are - * marked dirty and written out to disk, it doesn't - * really matter. - */ - pagefault_disable(); - copied = iov_iter_copy_from_user_atomic(page, i, - offset, bytes); - pagefault_enable(); - } else { - void *src, *dst; - src = kmap_atomic(src_page, KM_USER0); - dst = kmap_atomic(page, KM_USER1); - memcpy(dst + offset, src + offset, bytes); - kunmap_atomic(dst, KM_USER1); - kunmap_atomic(src, KM_USER0); - copied = bytes; - } - flush_dcache_page(page); - - status = a_ops->commit_write(file, page, offset, offset+bytes); - if (unlikely(status < 0)) - goto fs_write_aop_error; - if (unlikely(status > 0)) /* filesystem did partial write */ - copied = min_t(size_t, copied, status); - - unlock_page(page); - mark_page_accessed(page); - page_cache_release(page); - if (src_page) - page_cache_release(src_page); - - iov_iter_advance(i, copied); - pos += copied; - written += copied; - - balance_dirty_pages_ratelimited(mapping); - cond_resched(); - continue; - -fs_write_aop_error: - unlock_page(page); - page_cache_release(page); - if (src_page) - page_cache_release(src_page); - - /* - * 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); - break; - } while (iov_iter_count(i)); - - return written ? written : status; -} - static ssize_t generic_perform_write(struct file *file, struct iov_iter *i, loff_t pos) { @@ -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); + status = generic_perform_write(file, &i, pos); if (likely(status >= 0)) { written += status; |