diff options
Diffstat (limited to 'mm/filemap.c')
| -rw-r--r-- | mm/filemap.c | 35 |
1 files changed, 16 insertions, 19 deletions
diff --git a/mm/filemap.c b/mm/filemap.c index 1358cb061fd6..28c290da22c1 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -2394,23 +2394,20 @@ err: } /** - * generic_file_buffered_read - generic file read routine - * @iocb: the iocb to read - * @iter: data destination - * @written: already copied + * filemap_read - Read data from the page cache. + * @iocb: The iocb to read. + * @iter: Destination for the data. + * @already_read: Number of bytes already read by the caller. * - * This is a generic file read routine, and uses the - * mapping->a_ops->readpage() function for the actual low-level stuff. + * Copies data from the page cache. If the data is not currently present, + * uses the readahead and readpage address_space operations to fetch it. * - * This is really ugly. But the goto's actually try to clarify some - * of the logic when it comes to error handling etc. - * - * Return: - * * total number of bytes copied, including those the were already @written - * * negative error code if nothing was copied + * Return: Total number of bytes copied, including those already read by + * the caller. If an error happens before any bytes are copied, returns + * a negative error number. */ -ssize_t generic_file_buffered_read(struct kiocb *iocb, - struct iov_iter *iter, ssize_t written) +ssize_t filemap_read(struct kiocb *iocb, struct iov_iter *iter, + ssize_t already_read) { struct file *filp = iocb->ki_filp; struct file_ra_state *ra = &filp->f_ra; @@ -2437,7 +2434,7 @@ ssize_t generic_file_buffered_read(struct kiocb *iocb, * can no longer safely return -EIOCBQUEUED. Hence mark * an async read NOWAIT at that point. */ - if ((iocb->ki_flags & IOCB_WAITQ) && written) + if ((iocb->ki_flags & IOCB_WAITQ) && already_read) iocb->ki_flags |= IOCB_NOWAIT; error = filemap_get_pages(iocb, iter, &pvec); @@ -2497,7 +2494,7 @@ ssize_t generic_file_buffered_read(struct kiocb *iocb, copied = copy_page_to_iter(page, offset, bytes, iter); - written += copied; + already_read += copied; iocb->ki_pos += copied; ra->prev_pos = iocb->ki_pos; @@ -2514,9 +2511,9 @@ put_pages: file_accessed(filp); - return written ? written : error; + return already_read ? already_read : error; } -EXPORT_SYMBOL_GPL(generic_file_buffered_read); +EXPORT_SYMBOL_GPL(filemap_read); /** * generic_file_read_iter - generic filesystem read routine @@ -2591,7 +2588,7 @@ generic_file_read_iter(struct kiocb *iocb, struct iov_iter *iter) goto out; } - retval = generic_file_buffered_read(iocb, iter, retval); + retval = filemap_read(iocb, iter, retval); out: return retval; } |