diff options
| -rw-r--r-- | fs/fs-writeback.c | 133 | ||||
| -rw-r--r-- | include/linux/writeback.h | 3 |
2 files changed, 76 insertions, 60 deletions
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c index 76fc4d5..6841effa 100644 --- a/fs/fs-writeback.c +++ b/fs/fs-writeback.c @@ -553,108 +553,85 @@ select_queue: return ret; } -static void unpin_sb_for_writeback(struct super_block **psb) +static void unpin_sb_for_writeback(struct super_block *sb) { - struct super_block *sb = *psb; - - if (sb) { - up_read(&sb->s_umount); - put_super(sb); - *psb = NULL; - } + up_read(&sb->s_umount); + put_super(sb); } +enum sb_pin_state { + SB_PINNED, + SB_NOT_PINNED, + SB_PIN_FAILED +}; + /* * For WB_SYNC_NONE writeback, the caller does not have the sb pinned * before calling writeback. So make sure that we do pin it, so it doesn't * go away while we are writing inodes from it. - * - * Returns 0 if the super was successfully pinned (or pinning wasn't needed), - * 1 if we failed. */ -static int pin_sb_for_writeback(struct writeback_control *wbc, - struct inode *inode, struct super_block **psb) +static enum sb_pin_state pin_sb_for_writeback(struct writeback_control *wbc, + struct super_block *sb) { - struct super_block *sb = inode->i_sb; - - /* - * If this sb is already pinned, nothing more to do. If not and - * *psb is non-NULL, unpin the old one first - */ - if (sb == *psb) - return 0; - else if (*psb) - unpin_sb_for_writeback(psb); - /* * Caller must already hold the ref for this */ if (wbc->sync_mode == WB_SYNC_ALL) { WARN_ON(!rwsem_is_locked(&sb->s_umount)); - return 0; + return SB_NOT_PINNED; } - spin_lock(&sb_lock); sb->s_count++; if (down_read_trylock(&sb->s_umount)) { if (sb->s_root) { spin_unlock(&sb_lock); - goto pinned; + return SB_PINNED; } /* * umounted, drop rwsem again and fall through to failure */ up_read(&sb->s_umount); } - sb->s_count--; spin_unlock(&sb_lock); - return 1; -pinned: - *psb = sb; - return 0; + return SB_PIN_FAILED; } -static void writeback_inodes_wb(struct bdi_writeback *wb, - struct writeback_control *wbc) +/* + * Write a portion of b_io inodes which belong to @sb. + * If @wbc->sb != NULL, then find and write all such + * inodes. Otherwise write only ones which go sequentially + * in reverse order. + * Return 1, if the caller writeback routine should be + * interrupted. Otherwise return 0. + */ +static int writeback_sb_inodes(struct super_block *sb, + struct bdi_writeback *wb, + struct writeback_control *wbc) { - struct super_block *sb = wbc->sb, *pin_sb = NULL; - const unsigned long start = jiffies; /* livelock avoidance */ - - spin_lock(&inode_lock); - - if (!wbc->for_kupdate || list_empty(&wb->b_io)) - queue_io(wb, wbc->older_than_this); - while (!list_empty(&wb->b_io)) { - struct inode *inode = list_entry(wb->b_io.prev, - struct inode, i_list); long pages_skipped; - - /* - * super block given and doesn't match, skip this inode - */ - if (sb && sb != inode->i_sb) { + struct inode *inode = list_entry(wb->b_io.prev, + struct inode, i_list); + if (wbc->sb && sb != inode->i_sb) { + /* super block given and doesn't + match, skip this inode */ redirty_tail(inode); continue; } - + if (sb != inode->i_sb) + /* finish with this superblock */ + return 0; if (inode->i_state & (I_NEW | I_WILL_FREE)) { requeue_io(inode); continue; } - /* * Was this inode dirtied after sync_sb_inodes was called? * This keeps sync from extra jobs and livelock. */ - if (inode_dirtied_after(inode, start)) - break; - - if (pin_sb_for_writeback(wbc, inode, &pin_sb)) { - requeue_io(inode); - continue; - } + if (inode_dirtied_after(inode, wbc->wb_start)) + return 1; BUG_ON(inode->i_state & (I_FREEING | I_CLEAR)); __iget(inode); @@ -673,14 +650,50 @@ static void writeback_inodes_wb(struct bdi_writeback *wb, spin_lock(&inode_lock); if (wbc->nr_to_write <= 0) { wbc->more_io = 1; - break; + return 1; } if (!list_empty(&wb->b_more_io)) wbc->more_io = 1; } + /* b_io is empty */ + return 1; +} + +static void writeback_inodes_wb(struct bdi_writeback *wb, + struct writeback_control *wbc) +{ + int ret = 0; - unpin_sb_for_writeback(&pin_sb); + wbc->wb_start = jiffies; /* livelock avoidance */ + spin_lock(&inode_lock); + if (!wbc->for_kupdate || list_empty(&wb->b_io)) + queue_io(wb, wbc->older_than_this); + + while (!list_empty(&wb->b_io)) { + struct inode *inode = list_entry(wb->b_io.prev, + struct inode, i_list); + struct super_block *sb = inode->i_sb; + enum sb_pin_state state; + + if (wbc->sb && sb != wbc->sb) { + /* super block given and doesn't + match, skip this inode */ + redirty_tail(inode); + continue; + } + state = pin_sb_for_writeback(wbc, sb); + + if (state == SB_PIN_FAILED) { + requeue_io(inode); + continue; + } + ret = writeback_sb_inodes(sb, wb, wbc); + if (state == SB_PINNED) + unpin_sb_for_writeback(sb); + if (ret) + break; + } spin_unlock(&inode_lock); /* Leave any unwritten inodes on b_io */ } diff --git a/include/linux/writeback.h b/include/linux/writeback.h index 76e8903..36520de 100644 --- a/include/linux/writeback.h +++ b/include/linux/writeback.h @@ -34,6 +34,9 @@ struct writeback_control { enum writeback_sync_modes sync_mode; unsigned long *older_than_this; /* If !NULL, only write back inodes older than this */ + unsigned long wb_start; /* Time writeback_inodes_wb was + called. This is needed to avoid + extra jobs and livelock */ long nr_to_write; /* Write this many pages, and decrement this for each page written */ long pages_skipped; /* Pages which were not written */ |
