From 47279570a1fd14b1fbd75f020ae151d5ef20a7c4 Mon Sep 17 00:00:00 2001 From: Andrew Morton <akpm@zip.com.au> Date: Mon, 27 May 2002 05:12:22 -0700 Subject: [PATCH] [PATCH] relax nr_to_write requirements Relax the requirements on the writeback_mapping a_op. This function is passed the number of pages which it should write. The current fs-writeback.c code will get confused if the address_space writes back more pages than it was asked to. With this change the address_space may write more pages than required if that is convenient. Extent-based fileystems may wish to do this. --- Documentation/filesystems/Locking | 11 ++++++----- fs/fs-writeback.c | 4 ++-- 2 files changed, 8 insertions(+), 7 deletions(-) diff --git a/Documentation/filesystems/Locking b/Documentation/filesystems/Locking index cb0263288366..aff3575d2828 100644 --- a/Documentation/filesystems/Locking +++ b/Documentation/filesystems/Locking @@ -179,11 +179,12 @@ existing instances of this method ->sync_page() itself doesn't look well-defined... ->writeback_mapping() is used for periodic writeback and for -systemcall-initiated sync operations. The address_space should start -I/O against at least *nr_to_write pages. *nr_to_write must be decremented -for each page which is written. *nr_to_write must not go negative (this -will be relaxed later). If nr_to_write is NULL, all dirty pages must -be written. +systemcall-initiated sync operations. The address_space should start +I/O against at least *nr_to_write pages. *nr_to_write must be +decremented for each page which is written. The address_space +implementation may write more (or less) pages than *nr_to_write asks +for, but it should try to be reasonably close. If nr_to_write is NULL, +all dirty pages must be written. ->vm_writeback() is called from the VM. The address_space should start I/O against at least *nr_to_write pages, including the passed page. As diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c index 348b7bf6b8c0..c16577f9001d 100644 --- a/fs/fs-writeback.c +++ b/fs/fs-writeback.c @@ -257,7 +257,7 @@ static void sync_sb_inodes(struct super_block *sb, int sync_mode, if (current_is_pdflush()) writeback_release(bdi); - if (nr_to_write && *nr_to_write == 0) + if (nr_to_write && *nr_to_write <= 0) break; } out: @@ -301,7 +301,7 @@ void writeback_unlocked_inodes(int *nr_to_write, int sync_mode, older_than_this); spin_lock(&sb_lock); } - if (nr_to_write && *nr_to_write == 0) + if (nr_to_write && *nr_to_write <= 0) break; } spin_unlock(&sb_lock); -- 2.30.9