diff --git a/fs/inode.c b/fs/inode.c index bd4da9c5207e..259ebf438893 100644 --- a/fs/inode.c +++ b/fs/inode.c @@ -2010,67 +2010,57 @@ static int __remove_privs(struct user_namespace *mnt_userns, return notify_change(mnt_userns, dentry, &newattrs, NULL); } -/* - * Remove special file priviledges (suid, capabilities) when file is written - * to or truncated. - */ -int file_remove_privs(struct file *file) +static int __file_remove_privs(struct file *file, unsigned int flags) { struct dentry *dentry = file_dentry(file); struct inode *inode = file_inode(file); + int error; int kill; - int error = 0; - /* - * Fast path for nothing security related. - * As well for non-regular files, e.g. blkdev inodes. - * For example, blkdev_write_iter() might get here - * trying to remove privs which it is not allowed to. - */ if (IS_NOSEC(inode) || !S_ISREG(inode->i_mode)) return 0; kill = dentry_needs_remove_privs(dentry); - if (kill < 0) + if (kill <= 0) return kill; - if (kill) - error = __remove_privs(file_mnt_user_ns(file), dentry, kill); + + if (flags & IOCB_NOWAIT) + return -EAGAIN; + + error = __remove_privs(file_mnt_user_ns(file), dentry, kill); if (!error) inode_has_no_xattr(inode); return error; } -EXPORT_SYMBOL(file_remove_privs); /** - * file_update_time - update mtime and ctime time - * @file: file accessed + * file_remove_privs - remove special file privileges (suid, capabilities) + * @file: file to remove privileges from * - * Update the mtime and ctime members of an inode and mark the inode - * for writeback. Note that this function is meant exclusively for - * usage in the file write path of filesystems, and filesystems may - * choose to explicitly ignore update via this function with the - * S_NOCMTIME inode flag, e.g. for network filesystem where these - * timestamps are handled by the server. This can return an error for - * file systems who need to allocate space in order to update an inode. + * When file is modified by a write or truncation ensure that special + * file privileges are removed. + * + * Return: 0 on success, negative errno on failure. */ - -int file_update_time(struct file *file) +int file_remove_privs(struct file *file) +{ + return __file_remove_privs(file, 0); +} +EXPORT_SYMBOL(file_remove_privs); + +static int inode_needs_update_time(struct inode *inode, struct timespec64 *now) { - struct inode *inode = file_inode(file); - struct timespec64 now; int sync_it = 0; - int ret; /* First try to exhaust all avenues to not sync */ if (IS_NOCMTIME(inode)) return 0; - now = current_time(inode); - if (!timespec64_equal(&inode->i_mtime, &now)) + if (!timespec64_equal(&inode->i_mtime, now)) sync_it = S_MTIME; - if (!timespec64_equal(&inode->i_ctime, &now)) + if (!timespec64_equal(&inode->i_ctime, now)) sync_it |= S_CTIME; if (IS_I_VERSION(inode) && inode_iversion_need_inc(inode)) @@ -2079,37 +2069,127 @@ int file_update_time(struct file *file) if (!sync_it) return 0; - /* Finally allowed to write? Takes lock. */ - if (__mnt_want_write_file(file)) - return 0; + return sync_it; +} - ret = inode_update_time(inode, &now, sync_it); - __mnt_drop_write_file(file); +static int __file_update_time(struct file *file, struct timespec64 *now, + int sync_mode) +{ + int ret = 0; + struct inode *inode = file_inode(file); + + /* try to update time settings */ + if (!__mnt_want_write_file(file)) { + ret = inode_update_time(inode, now, sync_mode); + __mnt_drop_write_file(file); + } return ret; } + +/** + * file_update_time - update mtime and ctime time + * @file: file accessed + * + * Update the mtime and ctime members of an inode and mark the inode for + * writeback. Note that this function is meant exclusively for usage in + * the file write path of filesystems, and filesystems may choose to + * explicitly ignore updates via this function with the _NOCMTIME inode + * flag, e.g. for network filesystem where these imestamps are handled + * by the server. This can return an error for file systems who need to + * allocate space in order to update an inode. + * + * Return: 0 on success, negative errno on failure. + */ +int file_update_time(struct file *file) +{ + int ret; + struct inode *inode = file_inode(file); + struct timespec64 now = current_time(inode); + + ret = inode_needs_update_time(inode, &now); + if (ret <= 0) + return ret; + + return __file_update_time(file, &now, ret); +} EXPORT_SYMBOL(file_update_time); -/* Caller must hold the file's inode lock */ -int file_modified(struct file *file) +/** + * file_modified_flags - handle mandated vfs changes when modifying a file + * @file: file that was modified + * @flags: kiocb flags + * + * When file has been modified ensure that special + * file privileges are removed and time settings are updated. + * + * If IOCB_NOWAIT is set, special file privileges will not be removed and + * time settings will not be updated. It will return -EAGAIN. + * + * Context: Caller must hold the file's inode lock. + * + * Return: 0 on success, negative errno on failure. + */ +static int file_modified_flags(struct file *file, int flags) { - int err; + int ret; + struct inode *inode = file_inode(file); + struct timespec64 now = current_time(inode); /* * Clear the security bits if the process is not being run by root. * This keeps people from modifying setuid and setgid binaries. */ - err = file_remove_privs(file); - if (err) - return err; + ret = __file_remove_privs(file, flags); + if (ret) + return ret; if (unlikely(file->f_mode & FMODE_NOCMTIME)) return 0; - return file_update_time(file); + ret = inode_needs_update_time(inode, &now); + if (ret <= 0) + return ret; + if (flags & IOCB_NOWAIT) + return -EAGAIN; + + return __file_update_time(file, &now, ret); +} + +/** + * file_modified - handle mandated vfs changes when modifying a file + * @file: file that was modified + * + * When file has been modified ensure that special + * file privileges are removed and time settings are updated. + * + * Context: Caller must hold the file's inode lock. + * + * Return: 0 on success, negative errno on failure. + */ +int file_modified(struct file *file) +{ + return file_modified_flags(file, 0); } EXPORT_SYMBOL(file_modified); +/** + * kiocb_modified - handle mandated vfs changes when modifying a file + * @iocb: iocb that was modified + * + * When file has been modified ensure that special + * file privileges are removed and time settings are updated. + * + * Context: Caller must hold the file's inode lock. + * + * Return: 0 on success, negative errno on failure. + */ +int kiocb_modified(struct kiocb *iocb) +{ + return file_modified_flags(iocb->ki_filp, iocb->ki_flags); +} +EXPORT_SYMBOL_GPL(kiocb_modified); + int inode_needs_sync(struct inode *inode) { if (IS_SYNC(inode)) diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c index d2a9f699e17e..c681eacc389b 100644 --- a/fs/iomap/buffered-io.c +++ b/fs/iomap/buffered-io.c @@ -44,20 +44,28 @@ static inline struct iomap_page *to_iomap_page(struct folio *folio) static struct bio_set iomap_ioend_bioset; static struct iomap_page * -iomap_page_create(struct inode *inode, struct folio *folio) +iomap_page_create(struct inode *inode, struct folio *folio, unsigned int flags) { struct iomap_page *iop = to_iomap_page(folio); unsigned int nr_blocks = i_blocks_per_folio(inode, folio); + gfp_t gfp; if (iop || nr_blocks <= 1) return iop; + if (flags & IOMAP_NOWAIT) + gfp = GFP_NOWAIT; + else + gfp = GFP_NOFS | __GFP_NOFAIL; + iop = kzalloc(struct_size(iop, uptodate, BITS_TO_LONGS(nr_blocks)), - GFP_NOFS | __GFP_NOFAIL); - spin_lock_init(&iop->uptodate_lock); - if (folio_test_uptodate(folio)) - bitmap_fill(iop->uptodate, nr_blocks); - folio_attach_private(folio, iop); + gfp); + if (iop) { + spin_lock_init(&iop->uptodate_lock); + if (folio_test_uptodate(folio)) + bitmap_fill(iop->uptodate, nr_blocks); + folio_attach_private(folio, iop); + } return iop; } @@ -226,7 +234,7 @@ static int iomap_read_inline_data(const struct iomap_iter *iter, if (WARN_ON_ONCE(size > iomap->length)) return -EIO; if (offset > 0) - iop = iomap_page_create(iter->inode, folio); + iop = iomap_page_create(iter->inode, folio, iter->flags); else iop = to_iomap_page(folio); @@ -264,7 +272,7 @@ static loff_t iomap_readpage_iter(const struct iomap_iter *iter, return iomap_read_inline_data(iter, folio); /* zero post-eof blocks as the page may be mapped */ - iop = iomap_page_create(iter->inode, folio); + iop = iomap_page_create(iter->inode, folio, iter->flags); iomap_adjust_read_range(iter->inode, folio, &pos, length, &poff, &plen); if (plen == 0) goto done; @@ -547,10 +555,11 @@ static int __iomap_write_begin(const struct iomap_iter *iter, loff_t pos, size_t len, struct folio *folio) { const struct iomap *srcmap = iomap_iter_srcmap(iter); - struct iomap_page *iop = iomap_page_create(iter->inode, folio); + struct iomap_page *iop; loff_t block_size = i_blocksize(iter->inode); loff_t block_start = round_down(pos, block_size); loff_t block_end = round_up(pos + len, block_size); + unsigned int nr_blocks = i_blocks_per_folio(iter->inode, folio); size_t from = offset_in_folio(folio, pos), to = from + len; size_t poff, plen; @@ -558,6 +567,10 @@ static int __iomap_write_begin(const struct iomap_iter *iter, loff_t pos, return 0; folio_clear_error(folio); + iop = iomap_page_create(iter->inode, folio, iter->flags); + if ((iter->flags & IOMAP_NOWAIT) && !iop && nr_blocks > 1) + return -EAGAIN; + do { iomap_adjust_read_range(iter->inode, folio, &block_start, block_end - block_start, &poff, &plen); @@ -574,7 +587,12 @@ static int __iomap_write_begin(const struct iomap_iter *iter, loff_t pos, return -EIO; folio_zero_segments(folio, poff, from, to, poff + plen); } else { - int status = iomap_read_folio_sync(block_start, folio, + int status; + + if (iter->flags & IOMAP_NOWAIT) + return -EAGAIN; + + status = iomap_read_folio_sync(block_start, folio, poff, plen, srcmap); if (status) return status; @@ -603,6 +621,9 @@ static int iomap_write_begin(const struct iomap_iter *iter, loff_t pos, unsigned fgp = FGP_LOCK | FGP_WRITE | FGP_CREAT | FGP_STABLE | FGP_NOFS; int status = 0; + if (iter->flags & IOMAP_NOWAIT) + fgp |= FGP_NOWAIT; + BUG_ON(pos + len > iter->iomap.offset + iter->iomap.length); if (srcmap != &iter->iomap) BUG_ON(pos + len > srcmap->offset + srcmap->length); @@ -622,7 +643,7 @@ static int iomap_write_begin(const struct iomap_iter *iter, loff_t pos, folio = __filemap_get_folio(iter->inode->i_mapping, pos >> PAGE_SHIFT, fgp, mapping_gfp_mask(iter->inode->i_mapping)); if (!folio) { - status = -ENOMEM; + status = (iter->flags & IOMAP_NOWAIT) ? -EAGAIN : -ENOMEM; goto out_no_page; } if (pos + len > folio_pos(folio) + folio_size(folio)) @@ -740,6 +761,8 @@ static loff_t iomap_write_iter(struct iomap_iter *iter, struct iov_iter *i) loff_t pos = iter->pos; ssize_t written = 0; long status = 0; + struct address_space *mapping = iter->inode->i_mapping; + unsigned int bdp_flags = (iter->flags & IOMAP_NOWAIT) ? BDP_ASYNC : 0; do { struct folio *folio; @@ -752,6 +775,11 @@ static loff_t iomap_write_iter(struct iomap_iter *iter, struct iov_iter *i) bytes = min_t(unsigned long, PAGE_SIZE - offset, iov_iter_count(i)); again: + status = balance_dirty_pages_ratelimited_flags(mapping, + bdp_flags); + if (unlikely(status)) + break; + if (bytes > length) bytes = length; @@ -760,6 +788,10 @@ again: * Otherwise there's a nasty deadlock on copying from the * same page as we're writing to, without it being marked * up-to-date. + * + * For async buffered writes the assumption is that the user + * page has already been faulted in. This can be optimized by + * faulting the user page. */ if (unlikely(fault_in_iov_iter_readable(i, bytes) == bytes)) { status = -EFAULT; @@ -771,7 +803,7 @@ again: break; page = folio_file_page(folio, pos >> PAGE_SHIFT); - if (mapping_writably_mapped(iter->inode->i_mapping)) + if (mapping_writably_mapped(mapping)) flush_dcache_page(page); copied = copy_page_from_iter_atomic(page, offset, bytes, i); @@ -796,10 +828,12 @@ again: pos += status; written += status; length -= status; - - balance_dirty_pages_ratelimited(iter->inode->i_mapping); } while (iov_iter_count(i) && length); + if (status == -EAGAIN) { + iov_iter_revert(i, written); + return -EAGAIN; + } return written ? written : status; } @@ -815,6 +849,9 @@ iomap_file_buffered_write(struct kiocb *iocb, struct iov_iter *i, }; int ret; + if (iocb->ki_flags & IOCB_NOWAIT) + iter.flags |= IOMAP_NOWAIT; + while ((ret = iomap_iter(&iter, ops)) > 0) iter.processed = iomap_write_iter(&iter, i); if (iter.pos == iocb->ki_pos) @@ -1329,7 +1366,7 @@ iomap_writepage_map(struct iomap_writepage_ctx *wpc, struct writeback_control *wbc, struct inode *inode, struct folio *folio, u64 end_pos) { - struct iomap_page *iop = iomap_page_create(inode, folio); + struct iomap_page *iop = iomap_page_create(inode, folio, 0); struct iomap_ioend *ioend, *next; unsigned len = i_blocksize(inode); unsigned nblocks = i_blocks_per_folio(inode, folio); diff --git a/fs/read_write.c b/fs/read_write.c index 397da0236607..0131d0df0476 100644 --- a/fs/read_write.c +++ b/fs/read_write.c @@ -1663,7 +1663,9 @@ int generic_write_checks_count(struct kiocb *iocb, loff_t *count) if (iocb->ki_flags & IOCB_APPEND) iocb->ki_pos = i_size_read(inode); - if ((iocb->ki_flags & IOCB_NOWAIT) && !(iocb->ki_flags & IOCB_DIRECT)) + if ((iocb->ki_flags & IOCB_NOWAIT) && + !((iocb->ki_flags & IOCB_DIRECT) || + (file->f_mode & FMODE_BUF_WASYNC))) return -EINVAL; return generic_write_check_limits(iocb->ki_filp, iocb->ki_pos, count); diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c index 5a171c0b244b..8d9b14d2b912 100644 --- a/fs/xfs/xfs_file.c +++ b/fs/xfs/xfs_file.c @@ -410,7 +410,7 @@ restart: spin_unlock(&ip->i_flags_lock); out: - return file_modified(file); + return kiocb_modified(iocb); } static int @@ -700,12 +700,11 @@ xfs_file_buffered_write( bool cleared_space = false; unsigned int iolock; - if (iocb->ki_flags & IOCB_NOWAIT) - return -EOPNOTSUPP; - write_retry: iolock = XFS_IOLOCK_EXCL; - xfs_ilock(ip, iolock); + ret = xfs_ilock_iocb(iocb, iolock); + if (ret) + return ret; ret = xfs_file_write_checks(iocb, from, &iolock); if (ret) @@ -1165,7 +1164,7 @@ xfs_file_open( { if (xfs_is_shutdown(XFS_M(inode->i_sb))) return -EIO; - file->f_mode |= FMODE_NOWAIT | FMODE_BUF_RASYNC; + file->f_mode |= FMODE_NOWAIT | FMODE_BUF_RASYNC | FMODE_BUF_WASYNC; return generic_file_open(inode, file); } diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c index 5a393259a3a3..5d50fed291b4 100644 --- a/fs/xfs/xfs_iomap.c +++ b/fs/xfs/xfs_iomap.c @@ -664,7 +664,7 @@ xfs_ilock_for_iomap( unsigned flags, unsigned *lockmode) { - unsigned mode = XFS_ILOCK_SHARED; + unsigned int mode = *lockmode; bool is_write = flags & (IOMAP_WRITE | IOMAP_ZERO); /* @@ -742,7 +742,7 @@ xfs_direct_write_iomap_begin( int nimaps = 1, error = 0; bool shared = false; u16 iomap_flags = 0; - unsigned lockmode; + unsigned int lockmode = XFS_ILOCK_SHARED; ASSERT(flags & (IOMAP_WRITE | IOMAP_ZERO)); @@ -886,6 +886,7 @@ xfs_buffered_write_iomap_begin( bool eof = false, cow_eof = false, shared = false; int allocfork = XFS_DATA_FORK; int error = 0; + unsigned int lockmode = XFS_ILOCK_EXCL; if (xfs_is_shutdown(mp)) return -EIO; @@ -897,7 +898,9 @@ xfs_buffered_write_iomap_begin( ASSERT(!XFS_IS_REALTIME_INODE(ip)); - xfs_ilock(ip, XFS_ILOCK_EXCL); + error = xfs_ilock_for_iomap(ip, flags, &lockmode); + if (error) + return error; if (XFS_IS_CORRUPT(mp, !xfs_ifork_has_extents(&ip->i_df)) || XFS_TEST_ERROR(false, mp, XFS_ERRTAG_BMAPIFORMAT)) { @@ -1172,7 +1175,7 @@ xfs_read_iomap_begin( xfs_fileoff_t end_fsb = xfs_iomap_end_fsb(mp, offset, length); int nimaps = 1, error = 0; bool shared = false; - unsigned lockmode; + unsigned int lockmode = XFS_ILOCK_SHARED; ASSERT(!(flags & (IOMAP_WRITE | IOMAP_ZERO))); diff --git a/include/linux/fs.h b/include/linux/fs.h index ec2e35886779..9f131e559d05 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -180,6 +180,9 @@ typedef int (dio_iodone_t)(struct kiocb *iocb, loff_t offset, /* File supports async buffered reads */ #define FMODE_BUF_RASYNC ((__force fmode_t)0x40000000) +/* File supports async nowait buffered writes */ +#define FMODE_BUF_WASYNC ((__force fmode_t)0x80000000) + /* * Attribute flags. These should be or-ed together to figure out what * has been changed! @@ -2515,6 +2518,7 @@ static inline void file_accessed(struct file *file) } extern int file_modified(struct file *file); +int kiocb_modified(struct kiocb *iocb); int sync_inode_metadata(struct inode *inode, int wait); diff --git a/include/linux/writeback.h b/include/linux/writeback.h index da21d63f70e2..b8c9610c2313 100644 --- a/include/linux/writeback.h +++ b/include/linux/writeback.h @@ -364,7 +364,14 @@ void global_dirty_limits(unsigned long *pbackground, unsigned long *pdirty); unsigned long wb_calc_thresh(struct bdi_writeback *wb, unsigned long thresh); void wb_update_bandwidth(struct bdi_writeback *wb); + +/* Invoke balance dirty pages in async mode. */ +#define BDP_ASYNC 0x0001 + void balance_dirty_pages_ratelimited(struct address_space *mapping); +int balance_dirty_pages_ratelimited_flags(struct address_space *mapping, + unsigned int flags); + bool wb_over_bg_thresh(struct bdi_writeback *wb); typedef int (*writepage_t)(struct page *page, struct writeback_control *wbc, diff --git a/include/trace/events/io_uring.h b/include/trace/events/io_uring.h index 95a8cfaad15a..c5b21ff0ac85 100644 --- a/include/trace/events/io_uring.h +++ b/include/trace/events/io_uring.h @@ -630,6 +630,31 @@ TRACE_EVENT(io_uring_task_work_run, __entry->tctx, __entry->count, __entry->loops) ); +TRACE_EVENT(io_uring_short_write, + + TP_PROTO(void *ctx, u64 fpos, u64 wanted, u64 got), + + TP_ARGS(ctx, fpos, wanted, got), + + TP_STRUCT__entry( + __field(void *, ctx) + __field(u64, fpos) + __field(u64, wanted) + __field(u64, got) + ), + + TP_fast_assign( + __entry->ctx = ctx; + __entry->fpos = fpos; + __entry->wanted = wanted; + __entry->got = got; + ), + + TP_printk("ring %p, fpos %lld, wanted %lld, got %lld", + __entry->ctx, __entry->fpos, + __entry->wanted, __entry->got) +); + #endif /* _TRACE_IO_URING_H */ /* This part must be outside protection */ diff --git a/io_uring/rw.c b/io_uring/rw.c index c50a0d66d67a..2b784795103c 100644 --- a/io_uring/rw.c +++ b/io_uring/rw.c @@ -641,7 +641,7 @@ static inline int io_iter_do_read(struct io_rw *rw, struct iov_iter *iter) return -EINVAL; } -static bool need_read_all(struct io_kiocb *req) +static bool need_complete_io(struct io_kiocb *req) { return req->flags & REQ_F_ISREG || S_ISBLK(file_inode(req->file)->i_mode); @@ -775,7 +775,7 @@ int io_read(struct io_kiocb *req, unsigned int issue_flags) kfree(iovec); return IOU_ISSUE_SKIP_COMPLETE; } else if (ret == req->cqe.res || ret <= 0 || !force_nonblock || - (req->flags & REQ_F_NOWAIT) || !need_read_all(req)) { + (req->flags & REQ_F_NOWAIT) || !need_complete_io(req)) { /* read all, failed, already did sync or don't want to retry */ goto done; } @@ -870,9 +870,10 @@ int io_write(struct io_kiocb *req, unsigned int issue_flags) if (unlikely(!io_file_supports_nowait(req))) goto copy_iov; - /* file path doesn't support NOWAIT for non-direct_IO */ - if (force_nonblock && !(kiocb->ki_flags & IOCB_DIRECT) && - (req->flags & REQ_F_ISREG)) + /* File path supports NOWAIT for non-direct_IO only for block devices. */ + if (!(kiocb->ki_flags & IOCB_DIRECT) && + !(kiocb->ki_filp->f_mode & FMODE_BUF_WASYNC) && + (req->flags & REQ_F_ISREG)) goto copy_iov; kiocb->ki_flags |= IOCB_NOWAIT; @@ -928,13 +929,41 @@ int io_write(struct io_kiocb *req, unsigned int issue_flags) /* IOPOLL retry should happen for io-wq threads */ if (ret2 == -EAGAIN && (req->ctx->flags & IORING_SETUP_IOPOLL)) goto copy_iov; + + if (ret2 != req->cqe.res && ret2 >= 0 && need_complete_io(req)) { + struct io_async_rw *rw; + + trace_io_uring_short_write(req->ctx, kiocb->ki_pos - ret2, + req->cqe.res, ret2); + + /* This is a partial write. The file pos has already been + * updated, setup the async struct to complete the request + * in the worker. Also update bytes_done to account for + * the bytes already written. + */ + iov_iter_save_state(&s->iter, &s->iter_state); + ret = io_setup_async_rw(req, iovec, s, true); + + rw = req->async_data; + if (rw) + rw->bytes_done += ret2; + + if (kiocb->ki_flags & IOCB_WRITE) + kiocb_end_write(req); + return ret ? ret : -EAGAIN; + } done: ret = kiocb_done(req, ret2, issue_flags); } else { copy_iov: iov_iter_restore(&s->iter, &s->iter_state); ret = io_setup_async_rw(req, iovec, s, false); - return ret ?: -EAGAIN; + if (!ret) { + if (kiocb->ki_flags & IOCB_WRITE) + kiocb_end_write(req); + return -EAGAIN; + } + return ret; } /* it's reportedly faster than delegating the null check to kfree() */ if (iovec) diff --git a/mm/filemap.c b/mm/filemap.c index ffdfbc8b0e3c..254931a6e3ed 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -1988,6 +1988,10 @@ no_page: gfp |= __GFP_WRITE; if (fgp_flags & FGP_NOFS) gfp &= ~__GFP_FS; + if (fgp_flags & FGP_NOWAIT) { + gfp &= ~GFP_KERNEL; + gfp |= GFP_NOWAIT | __GFP_NOWARN; + } folio = filemap_alloc_folio(gfp, 0); if (!folio) diff --git a/mm/page-writeback.c b/mm/page-writeback.c index 55c2776ae699..d0d466a5c804 100644 --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -1554,8 +1554,8 @@ static inline void wb_dirty_limits(struct dirty_throttle_control *dtc) * If we're over `background_thresh' then the writeback threads are woken to * perform some writeout. */ -static void balance_dirty_pages(struct bdi_writeback *wb, - unsigned long pages_dirtied) +static int balance_dirty_pages(struct bdi_writeback *wb, + unsigned long pages_dirtied, unsigned int flags) { struct dirty_throttle_control gdtc_stor = { GDTC_INIT(wb) }; struct dirty_throttle_control mdtc_stor = { MDTC_INIT(wb, &gdtc_stor) }; @@ -1575,6 +1575,7 @@ static void balance_dirty_pages(struct bdi_writeback *wb, struct backing_dev_info *bdi = wb->bdi; bool strictlimit = bdi->capabilities & BDI_CAP_STRICTLIMIT; unsigned long start_time = jiffies; + int ret = 0; for (;;) { unsigned long now = jiffies; @@ -1627,6 +1628,19 @@ static void balance_dirty_pages(struct bdi_writeback *wb, } } + /* + * In laptop mode, we wait until hitting the higher threshold + * before starting background writeout, and then write out all + * the way down to the lower threshold. So slow writers cause + * minimal disk activity. + * + * In normal mode, we start background writeout at the lower + * background_thresh, to keep the amount of dirty memory low. + */ + if (!laptop_mode && nr_reclaimable > gdtc->bg_thresh && + !writeback_in_progress(wb)) + wb_start_background_writeback(wb); + /* * Throttle it only when the background writeback cannot * catch-up. This avoids (excessively) small writeouts @@ -1657,6 +1671,7 @@ free_running: break; } + /* Start writeback even when in laptop mode */ if (unlikely(!writeback_in_progress(wb))) wb_start_background_writeback(wb); @@ -1715,8 +1730,8 @@ free_running: sdtc = mdtc; } - if (dirty_exceeded && !wb->dirty_exceeded) - wb->dirty_exceeded = 1; + if (dirty_exceeded != wb->dirty_exceeded) + wb->dirty_exceeded = dirty_exceeded; if (time_is_before_jiffies(READ_ONCE(wb->bw_time_stamp) + BANDWIDTH_INTERVAL)) @@ -1789,6 +1804,10 @@ pause: period, pause, start_time); + if (flags & BDP_ASYNC) { + ret = -EAGAIN; + break; + } __set_current_state(TASK_KILLABLE); wb->dirty_sleep = now; io_schedule_timeout(pause); @@ -1820,26 +1839,7 @@ pause: if (fatal_signal_pending(current)) break; } - - if (!dirty_exceeded && wb->dirty_exceeded) - wb->dirty_exceeded = 0; - - if (writeback_in_progress(wb)) - return; - - /* - * In laptop mode, we wait until hitting the higher threshold before - * starting background writeout, and then write out all the way down - * to the lower threshold. So slow writers cause minimal disk activity. - * - * In normal mode, we start background writeout at the lower - * background_thresh, to keep the amount of dirty memory low. - */ - if (laptop_mode) - return; - - if (nr_reclaimable > gdtc->bg_thresh) - wb_start_background_writeback(wb); + return ret; } static DEFINE_PER_CPU(int, bdp_ratelimits); @@ -1861,27 +1861,34 @@ static DEFINE_PER_CPU(int, bdp_ratelimits); DEFINE_PER_CPU(int, dirty_throttle_leaks) = 0; /** - * balance_dirty_pages_ratelimited - balance dirty memory state - * @mapping: address_space which was dirtied + * balance_dirty_pages_ratelimited_flags - Balance dirty memory state. + * @mapping: address_space which was dirtied. + * @flags: BDP flags. * * Processes which are dirtying memory should call in here once for each page * which was newly dirtied. The function will periodically check the system's * dirty state and will initiate writeback if needed. * - * Once we're over the dirty memory limit we decrease the ratelimiting - * by a lot, to prevent individual processes from overshooting the limit - * by (ratelimit_pages) each. + * See balance_dirty_pages_ratelimited() for details. + * + * Return: If @flags contains BDP_ASYNC, it may return -EAGAIN to + * indicate that memory is out of balance and the caller must wait + * for I/O to complete. Otherwise, it will return 0 to indicate + * that either memory was already in balance, or it was able to sleep + * until the amount of dirty memory returned to balance. */ -void balance_dirty_pages_ratelimited(struct address_space *mapping) +int balance_dirty_pages_ratelimited_flags(struct address_space *mapping, + unsigned int flags) { struct inode *inode = mapping->host; struct backing_dev_info *bdi = inode_to_bdi(inode); struct bdi_writeback *wb = NULL; int ratelimit; + int ret = 0; int *p; if (!(bdi->capabilities & BDI_CAP_WRITEBACK)) - return; + return ret; if (inode_cgwb_enabled(inode)) wb = wb_get_create_current(bdi, GFP_KERNEL); @@ -1921,9 +1928,27 @@ void balance_dirty_pages_ratelimited(struct address_space *mapping) preempt_enable(); if (unlikely(current->nr_dirtied >= ratelimit)) - balance_dirty_pages(wb, current->nr_dirtied); + ret = balance_dirty_pages(wb, current->nr_dirtied, flags); wb_put(wb); + return ret; +} + +/** + * balance_dirty_pages_ratelimited - balance dirty memory state. + * @mapping: address_space which was dirtied. + * + * Processes which are dirtying memory should call in here once for each page + * which was newly dirtied. The function will periodically check the system's + * dirty state and will initiate writeback if needed. + * + * Once we're over the dirty memory limit we decrease the ratelimiting + * by a lot, to prevent individual processes from overshooting the limit + * by (ratelimit_pages) each. + */ +void balance_dirty_pages_ratelimited(struct address_space *mapping) +{ + balance_dirty_pages_ratelimited_flags(mapping, 0); } EXPORT_SYMBOL(balance_dirty_pages_ratelimited);