diff options
| -rw-r--r-- | include/linux/fs.h | 3 | ||||
| -rw-r--r-- | include/linux/pipe_fs_i.h | 20 | ||||
| -rw-r--r-- | lib/iov_iter.c | 6 | ||||
| -rw-r--r-- | mm/filemap.c | 129 | ||||
| -rw-r--r-- | mm/internal.h | 6 |
5 files changed, 158 insertions, 6 deletions
diff --git a/include/linux/fs.h b/include/linux/fs.h index c1769a2c5d70..28743e38df91 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -3163,6 +3163,9 @@ ssize_t vfs_iocb_iter_write(struct file *file, struct kiocb *iocb, struct iov_iter *iter); /* fs/splice.c */ +ssize_t filemap_splice_read(struct file *in, loff_t *ppos, + struct pipe_inode_info *pipe, + size_t len, unsigned int flags); extern ssize_t generic_file_splice_read(struct file *, loff_t *, struct pipe_inode_info *, size_t, unsigned int); extern ssize_t iter_file_splice_write(struct pipe_inode_info *, diff --git a/include/linux/pipe_fs_i.h b/include/linux/pipe_fs_i.h index 6cb65df3e3ba..d2c3f16cf6b1 100644 --- a/include/linux/pipe_fs_i.h +++ b/include/linux/pipe_fs_i.h @@ -157,6 +157,26 @@ static inline bool pipe_full(unsigned int head, unsigned int tail, } /** + * pipe_buf - Return the pipe buffer for the specified slot in the pipe ring + * @pipe: The pipe to access + * @slot: The slot of interest + */ +static inline struct pipe_buffer *pipe_buf(const struct pipe_inode_info *pipe, + unsigned int slot) +{ + return &pipe->bufs[slot & (pipe->ring_size - 1)]; +} + +/** + * pipe_head_buf - Return the pipe buffer at the head of the pipe ring + * @pipe: The pipe to access + */ +static inline struct pipe_buffer *pipe_head_buf(const struct pipe_inode_info *pipe) +{ + return pipe_buf(pipe, pipe->head); +} + +/** * pipe_buf_get - get a reference to a pipe_buffer * @pipe: the pipe that the buffer belongs to * @buf: the buffer to get a reference to diff --git a/lib/iov_iter.c b/lib/iov_iter.c index f9a3ff37ecd1..47c484551c59 100644 --- a/lib/iov_iter.c +++ b/lib/iov_iter.c @@ -186,12 +186,6 @@ static int copyin(void *to, const void __user *from, size_t n) return res; } -static inline struct pipe_buffer *pipe_buf(const struct pipe_inode_info *pipe, - unsigned int slot) -{ - return &pipe->bufs[slot & (pipe->ring_size - 1)]; -} - #ifdef PIPE_PARANOIA static bool sanity(const struct iov_iter *i) { diff --git a/mm/filemap.c b/mm/filemap.c index 2d5377012284..162b4daaeb99 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -42,6 +42,8 @@ #include <linux/ramfs.h> #include <linux/page_idle.h> #include <linux/migrate.h> +#include <linux/pipe_fs_i.h> +#include <linux/splice.h> #include <asm/pgalloc.h> #include <asm/tlbflush.h> #include "internal.h" @@ -2843,6 +2845,133 @@ generic_file_read_iter(struct kiocb *iocb, struct iov_iter *iter) } EXPORT_SYMBOL(generic_file_read_iter); +/* + * Splice subpages from a folio into a pipe. + */ +size_t splice_folio_into_pipe(struct pipe_inode_info *pipe, + struct folio *folio, loff_t fpos, size_t size) +{ + struct page *page; + size_t spliced = 0, offset = offset_in_folio(folio, fpos); + + page = folio_page(folio, offset / PAGE_SIZE); + size = min(size, folio_size(folio) - offset); + offset %= PAGE_SIZE; + + while (spliced < size && + !pipe_full(pipe->head, pipe->tail, pipe->max_usage)) { + struct pipe_buffer *buf = pipe_head_buf(pipe); + size_t part = min_t(size_t, PAGE_SIZE - offset, size - spliced); + + *buf = (struct pipe_buffer) { + .ops = &page_cache_pipe_buf_ops, + .page = page, + .offset = offset, + .len = part, + }; + folio_get(folio); + pipe->head++; + page++; + spliced += part; + offset = 0; + } + + return spliced; +} + +/* + * Splice folios from the pagecache of a buffered (ie. non-O_DIRECT) file into + * a pipe. + */ +ssize_t filemap_splice_read(struct file *in, loff_t *ppos, + struct pipe_inode_info *pipe, + size_t len, unsigned int flags) +{ + struct folio_batch fbatch; + struct kiocb iocb; + size_t total_spliced = 0, used, npages; + loff_t isize, end_offset; + bool writably_mapped; + int i, error = 0; + + init_sync_kiocb(&iocb, in); + iocb.ki_pos = *ppos; + + /* Work out how much data we can actually add into the pipe */ + used = pipe_occupancy(pipe->head, pipe->tail); + npages = max_t(ssize_t, pipe->max_usage - used, 0); + len = min_t(size_t, len, npages * PAGE_SIZE); + + folio_batch_init(&fbatch); + + do { + cond_resched(); + + if (*ppos >= i_size_read(file_inode(in))) + break; + + iocb.ki_pos = *ppos; + error = filemap_get_pages(&iocb, len, &fbatch, true); + if (error < 0) + break; + + /* + * i_size must be checked after we know the pages are Uptodate. + * + * Checking i_size after the check allows us to calculate + * the correct value for "nr", which means the zero-filled + * part of the page is not copied back to userspace (unless + * another truncate extends the file - this is desired though). + */ + isize = i_size_read(file_inode(in)); + if (unlikely(*ppos >= isize)) + break; + end_offset = min_t(loff_t, isize, *ppos + len); + + /* + * Once we start copying data, we don't want to be touching any + * cachelines that might be contended: + */ + writably_mapped = mapping_writably_mapped(in->f_mapping); + + for (i = 0; i < folio_batch_count(&fbatch); i++) { + struct folio *folio = fbatch.folios[i]; + size_t n; + + if (folio_pos(folio) >= end_offset) + goto out; + folio_mark_accessed(folio); + + /* + * If users can be writing to this folio using arbitrary + * virtual addresses, take care of potential aliasing + * before reading the folio on the kernel side. + */ + if (writably_mapped) + flush_dcache_folio(folio); + + n = min_t(loff_t, len, isize - *ppos); + n = splice_folio_into_pipe(pipe, folio, *ppos, n); + if (!n) + goto out; + len -= n; + total_spliced += n; + *ppos += n; + in->f_ra.prev_pos = *ppos; + if (pipe_full(pipe->head, pipe->tail, pipe->max_usage)) + goto out; + } + + folio_batch_release(&fbatch); + } while (len); + +out: + folio_batch_release(&fbatch); + file_accessed(in); + + return total_spliced ? total_spliced : error; +} + static inline loff_t folio_seek_hole_data(struct xa_state *xas, struct address_space *mapping, struct folio *folio, loff_t start, loff_t end, bool seek_data) diff --git a/mm/internal.h b/mm/internal.h index bcf75a8b032d..6d4ca98f3844 100644 --- a/mm/internal.h +++ b/mm/internal.h @@ -795,6 +795,12 @@ struct migration_target_control { }; /* + * mm/filemap.c + */ +size_t splice_folio_into_pipe(struct pipe_inode_info *pipe, + struct folio *folio, loff_t fpos, size_t size); + +/* * mm/vmalloc.c */ #ifdef CONFIG_MMU |