diff options
| -rw-r--r-- | fs/pipe.c | 4 | ||||
| -rw-r--r-- | fs/splice.c | 177 | ||||
| -rw-r--r-- | include/linux/pipe_fs_i.h | 6 |
3 files changed, 146 insertions, 41 deletions
diff --git a/fs/pipe.c b/fs/pipe.c index 109a102c150..795df987cd3 100644 --- a/fs/pipe.c +++ b/fs/pipe.c @@ -95,6 +95,8 @@ static void anon_pipe_buf_release(struct pipe_inode_info *info, struct pipe_buff { struct page *page = buf->page; + buf->flags &= ~PIPE_BUF_FLAG_STOLEN; + /* * If nobody else uses this page, and we don't already have a * temporary page, let's keep track of it as a one-deep @@ -124,7 +126,7 @@ static void anon_pipe_buf_unmap(struct pipe_inode_info *info, struct pipe_buffer static int anon_pipe_buf_steal(struct pipe_inode_info *info, struct pipe_buffer *buf) { - buf->stolen = 1; + buf->flags |= PIPE_BUF_FLAG_STOLEN; return 0; } diff --git a/fs/splice.c b/fs/splice.c index 6081cf7d2d1..bfa42a277bb 100644 --- a/fs/splice.c +++ b/fs/splice.c @@ -22,7 +22,10 @@ #include <linux/pipe_fs_i.h> #include <linux/mm_inline.h> #include <linux/swap.h> +#include <linux/writeback.h> +#include <linux/buffer_head.h> #include <linux/module.h> +#include <linux/syscalls.h> /* * Passed to the actors @@ -34,28 +37,37 @@ struct splice_desc { loff_t pos; /* file position */ }; +/* + * Attempt to steal a page from a pipe buffer. This should perhaps go into + * a vm helper function, it's already simplified quite a bit by the + * addition of remove_mapping(). If success is returned, the caller may + * attempt to reuse this page for another destination. + */ static int page_cache_pipe_buf_steal(struct pipe_inode_info *info, struct pipe_buffer *buf) { struct page *page = buf->page; + struct address_space *mapping = page_mapping(page); WARN_ON(!PageLocked(page)); WARN_ON(!PageUptodate(page)); - if (!remove_mapping(page_mapping(page), page)) - return 1; + /* + * At least for ext2 with nobh option, we need to wait on writeback + * completing on this page, since we'll remove it from the pagecache. + * Otherwise truncate wont wait on the page, allowing the disk + * blocks to be reused by someone else before we actually wrote our + * data to them. fs corruption ensues. + */ + wait_on_page_writeback(page); - if (PageLRU(page)) { - struct zone *zone = page_zone(page); + if (PagePrivate(page)) + try_to_release_page(page, mapping_gfp_mask(mapping)); - spin_lock_irq(&zone->lru_lock); - BUG_ON(!PageLRU(page)); - __ClearPageLRU(page); - del_page_from_lru(zone, page); - spin_unlock_irq(&zone->lru_lock); - } + if (!remove_mapping(mapping, page)) + return 1; - buf->stolen = 1; + buf->flags |= PIPE_BUF_FLAG_STOLEN | PIPE_BUF_FLAG_LRU; return 0; } @@ -64,7 +76,7 @@ static void page_cache_pipe_buf_release(struct pipe_inode_info *info, { page_cache_release(buf->page); buf->page = NULL; - buf->stolen = 0; + buf->flags &= ~(PIPE_BUF_FLAG_STOLEN | PIPE_BUF_FLAG_LRU); } static void *page_cache_pipe_buf_map(struct file *file, @@ -91,8 +103,7 @@ static void *page_cache_pipe_buf_map(struct file *file, static void page_cache_pipe_buf_unmap(struct pipe_inode_info *info, struct pipe_buffer *buf) { - if (!buf->stolen) - unlock_page(buf->page); + unlock_page(buf->page); kunmap(buf->page); } @@ -104,6 +115,10 @@ static struct pipe_buf_operations page_cache_pipe_buf_ops = { .steal = page_cache_pipe_buf_steal, }; +/* + * Pipe output worker. This sets up our pipe format with the page cache + * pipe buffer operations. Otherwise very similar to the regular pipe_writev(). + */ static ssize_t move_to_pipe(struct inode *inode, struct page **pages, int nr_pages, unsigned long offset, unsigned long len, unsigned int flags) @@ -237,9 +252,9 @@ static int __generic_file_splice_read(struct file *in, struct inode *pipe, * fill shadow[] with pages at the right locations, so we only * have to fill holes */ - memset(shadow, 0, i * sizeof(struct page *)); - for (j = 0, pidx = index; j < i; pidx++, j++) - shadow[pages[j]->index - pidx] = pages[j]; + memset(shadow, 0, nr_pages * sizeof(struct page *)); + for (j = 0; j < i; j++) + shadow[pages[j]->index - index] = pages[j]; /* * now fill in the holes @@ -288,6 +303,16 @@ splice_them: return move_to_pipe(pipe, pages, i, offset, len, flags); } +/** + * generic_file_splice_read - splice data from file to a pipe + * @in: file to splice from + * @pipe: pipe to splice to + * @len: number of bytes to splice + * @flags: splice modifier flags + * + * Will read pages from given file and fill them into a pipe. + * + */ ssize_t generic_file_splice_read(struct file *in, struct inode *pipe, size_t len, unsigned int flags) { @@ -318,8 +343,11 @@ ssize_t generic_file_splice_read(struct file *in, struct inode *pipe, return ret; } +EXPORT_SYMBOL(generic_file_splice_read); + /* - * Send 'len' bytes to socket from 'file' at position 'pos' using sendpage(). + * Send 'sd->len' bytes to socket from 'sd->file' at position 'sd->pos' + * using sendpage(). */ static int pipe_to_sendpage(struct pipe_inode_info *info, struct pipe_buffer *buf, struct splice_desc *sd) @@ -329,6 +357,7 @@ static int pipe_to_sendpage(struct pipe_inode_info *info, unsigned int offset; ssize_t ret; void *ptr; + int more; /* * sub-optimal, but we are limited by the pipe ->map. we don't @@ -341,9 +370,9 @@ static int pipe_to_sendpage(struct pipe_inode_info *info, return PTR_ERR(ptr); offset = pos & ~PAGE_CACHE_MASK; + more = (sd->flags & SPLICE_F_MORE) || sd->len < sd->total_len; - ret = file->f_op->sendpage(file, buf->page, offset, sd->len, &pos, - sd->len < sd->total_len); + ret = file->f_op->sendpage(file, buf->page, offset, sd->len, &pos,more); buf->ops->unmap(info, buf); if (ret == sd->len) @@ -365,16 +394,19 @@ static int pipe_to_sendpage(struct pipe_inode_info *info, * - Destination page does not exist, we can add the pipe page to * the page cache and avoid the copy. * - * For now we just do the slower thing and always copy pages over, it's - * easier than migrating pages from the pipe to the target file. For the - * case of doing file | file splicing, the migrate approach had some LRU - * nastiness... + * If asked to move pages to the output file (SPLICE_F_MOVE is set in + * sd->flags), we attempt to migrate pages from the pipe to the output + * file address space page cache. This is possible if no one else has + * the pipe page referenced outside of the pipe and page cache. If + * SPLICE_F_MOVE isn't set, or we cannot move the page, we simply create + * a new page in the output file page cache and fill/dirty that. */ static int pipe_to_file(struct pipe_inode_info *info, struct pipe_buffer *buf, struct splice_desc *sd) { struct file *file = sd->file; struct address_space *mapping = file->f_mapping; + gfp_t gfp_mask = mapping_gfp_mask(mapping); unsigned int offset; struct page *page; pgoff_t index; @@ -395,18 +427,23 @@ static int pipe_to_file(struct pipe_inode_info *info, struct pipe_buffer *buf, * reuse buf page, if SPLICE_F_MOVE is set */ if (sd->flags & SPLICE_F_MOVE) { + /* + * If steal succeeds, buf->page is now pruned from the vm + * side (LRU and page cache) and we can reuse it. + */ if (buf->ops->steal(info, buf)) goto find_page; page = buf->page; - if (add_to_page_cache_lru(page, mapping, index, - mapping_gfp_mask(mapping))) + if (add_to_page_cache(page, mapping, index, gfp_mask)) goto find_page; + + if (!(buf->flags & PIPE_BUF_FLAG_LRU)) + lru_cache_add(page); } else { find_page: ret = -ENOMEM; - page = find_or_create_page(mapping, index, - mapping_gfp_mask(mapping)); + page = find_or_create_page(mapping, index, gfp_mask); if (!page) goto out; @@ -443,10 +480,13 @@ find_page: } ret = mapping->a_ops->prepare_write(file, page, 0, sd->len); - if (ret) + if (ret == AOP_TRUNCATED_PAGE) { + page_cache_release(page); + goto find_page; + } else if (ret) goto out; - if (!buf->stolen) { + if (!(buf->flags & PIPE_BUF_FLAG_STOLEN)) { char *dst = kmap_atomic(page, KM_USER0); memcpy(dst + offset, src + buf->offset, sd->len); @@ -455,16 +495,18 @@ find_page: } ret = mapping->a_ops->commit_write(file, page, 0, sd->len); - if (ret < 0) + if (ret == AOP_TRUNCATED_PAGE) { + page_cache_release(page); + goto find_page; + } else if (ret) goto out; - set_page_dirty(page); - ret = write_one_page(page, 0); + balance_dirty_pages_ratelimited(mapping); out: - if (ret < 0) - unlock_page(page); - if (!buf->stolen) + if (!(buf->flags & PIPE_BUF_FLAG_STOLEN)) { page_cache_release(page); + unlock_page(page); + } buf->ops->unmap(info, buf); return ret; } @@ -472,6 +514,11 @@ out: typedef int (splice_actor)(struct pipe_inode_info *, struct pipe_buffer *, struct splice_desc *); +/* + * Pipe input worker. Most of this logic works like a regular pipe, the + * key here is the 'actor' worker passed in that actually moves the data + * to the wanted destination. See pipe_to_file/pipe_to_sendpage above. + */ static ssize_t move_from_pipe(struct inode *inode, struct file *out, size_t len, unsigned int flags, splice_actor *actor) @@ -573,21 +620,67 @@ static ssize_t move_from_pipe(struct inode *inode, struct file *out, } +/** + * generic_file_splice_write - splice data from a pipe to a file + * @inode: pipe inode + * @out: file to write to + * @len: number of bytes to splice + * @flags: splice modifier flags + * + * Will either move or copy pages (determined by @flags options) from + * the given pipe inode to the given file. + * + */ ssize_t generic_file_splice_write(struct inode *inode, struct file *out, size_t len, unsigned int flags) { - return move_from_pipe(inode, out, len, flags, pipe_to_file); + struct address_space *mapping = out->f_mapping; + ssize_t ret = move_from_pipe(inode, out, len, flags, pipe_to_file); + + /* + * if file or inode is SYNC and we actually wrote some data, sync it + */ + if (unlikely((out->f_flags & O_SYNC) || IS_SYNC(mapping->host)) + && ret > 0) { + struct inode *inode = mapping->host; + int err; + + mutex_lock(&inode->i_mutex); + err = generic_osync_inode(mapping->host, mapping, + OSYNC_METADATA|OSYNC_DATA); + mutex_unlock(&inode->i_mutex); + + if (err) + ret = err; + } + + return ret; } +EXPORT_SYMBOL(generic_file_splice_write); + +/** + * generic_splice_sendpage - splice data from a pipe to a socket + * @inode: pipe inode + * @out: socket to write to + * @len: number of bytes to splice + * @flags: splice modifier flags + * + * Will send @len bytes from the pipe to a network socket. No data copying + * is involved. + * + */ ssize_t generic_splice_sendpage(struct inode *inode, struct file *out, size_t len, unsigned int flags) { return move_from_pipe(inode, out, len, flags, pipe_to_sendpage); } -EXPORT_SYMBOL(generic_file_splice_write); -EXPORT_SYMBOL(generic_file_splice_read); +EXPORT_SYMBOL(generic_splice_sendpage); +/* + * Attempt to initiate a splice from pipe to file. + */ static long do_splice_from(struct inode *pipe, struct file *out, size_t len, unsigned int flags) { @@ -608,6 +701,9 @@ static long do_splice_from(struct inode *pipe, struct file *out, size_t len, return out->f_op->splice_write(pipe, out, len, flags); } +/* + * Attempt to initiate a splice from a file to a pipe. + */ static long do_splice_to(struct file *in, struct inode *pipe, size_t len, unsigned int flags) { @@ -636,6 +732,9 @@ static long do_splice_to(struct file *in, struct inode *pipe, size_t len, return in->f_op->splice_read(in, pipe, len, flags); } +/* + * Determine where to splice to/from. + */ static long do_splice(struct file *in, struct file *out, size_t len, unsigned int flags) { diff --git a/include/linux/pipe_fs_i.h b/include/linux/pipe_fs_i.h index d218fc72931..ec384958d50 100644 --- a/include/linux/pipe_fs_i.h +++ b/include/linux/pipe_fs_i.h @@ -5,11 +5,14 @@ #define PIPE_BUFFERS (16) +#define PIPE_BUF_FLAG_STOLEN 0x01 +#define PIPE_BUF_FLAG_LRU 0x02 + struct pipe_buffer { struct page *page; unsigned int offset, len; struct pipe_buf_operations *ops; - unsigned int stolen; + unsigned int flags; }; struct pipe_buf_operations { @@ -63,5 +66,6 @@ void free_pipe_info(struct inode* inode); #define SPLICE_F_NONBLOCK (0x02) /* don't block on the pipe splicing (but */ /* we may still block on the fd we splice */ /* from/to, of course */ +#define SPLICE_F_MORE (0x04) /* expect more data */ #endif |