ext4: revert "ext4: use io_end for multiple bios"

This reverts commit 4eec708d263f0ee10861d69251708a225b64cac7.

Multiple users have reported crashes which is apparently caused by
this commit.  Thanks to Dmitry Monakhov for bisecting it.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: Dmitry Monakhov <dmonakhov@openvz.org>
Cc: Jan Kara <jack@suse.cz>

1 files changed, 45 insertions, 76 deletions

diff --git a/fs/ext4/page-io.c b/fs/ext4/page-io.c
index 5929cd0baa20..6626aba57ebb 100644
--- a/fs/ext4/page-io.c
+++ b/fs/ext4/page-io.c
@@ -61,28 +61,15 @@ void ext4_ioend_shutdown(struct inode *inode)
                 cancel_work_sync(&EXT4_I(inode)->i_unwritten_work);
 }
 
-static void ext4_release_io_end(ext4_io_end_t *io_end)
+void ext4_free_io_end(ext4_io_end_t *io)
 {
-        BUG_ON(!list_empty(&io_end->list));
-        BUG_ON(io_end->flag & EXT4_IO_END_UNWRITTEN);
-
-        if (atomic_dec_and_test(&EXT4_I(io_end->inode)->i_ioend_count))
-                wake_up_all(ext4_ioend_wq(io_end->inode));
-        if (io_end->flag & EXT4_IO_END_DIRECT)
-                inode_dio_done(io_end->inode);
-        if (io_end->iocb)
-                aio_complete(io_end->iocb, io_end->result, 0);
-        kmem_cache_free(io_end_cachep, io_end);
-}
-
-static void ext4_clear_io_unwritten_flag(ext4_io_end_t *io_end)
-{
-        struct inode *inode = io_end->inode;
+        BUG_ON(!io);
+        BUG_ON(!list_empty(&io->list));
+        BUG_ON(io->flag & EXT4_IO_END_UNWRITTEN);
 
-        io_end->flag &= ~EXT4_IO_END_UNWRITTEN;
-        /* Wake up anyone waiting on unwritten extent conversion */
-        if (atomic_dec_and_test(&EXT4_I(inode)->i_unwritten))
-                wake_up_all(ext4_ioend_wq(inode));
+        if (atomic_dec_and_test(&EXT4_I(io->inode)->i_ioend_count))
+                wake_up_all(ext4_ioend_wq(io->inode));
+        kmem_cache_free(io_end_cachep, io);
 }
 
 /* check a range of space and convert unwritten extents to written. */
@@ -105,8 +92,13 @@ static int ext4_end_io(ext4_io_end_t *io)
                          "(inode %lu, offset %llu, size %zd, error %d)",
                          inode->i_ino, offset, size, ret);
         }
-        ext4_clear_io_unwritten_flag(io);
-        ext4_release_io_end(io);
+        /* Wake up anyone waiting on unwritten extent conversion */
+        if (atomic_dec_and_test(&EXT4_I(inode)->i_unwritten))
+                wake_up_all(ext4_ioend_wq(inode));
+        if (io->flag & EXT4_IO_END_DIRECT)
+                inode_dio_done(inode);
+        if (io->iocb)
+                aio_complete(io->iocb, io->result, 0);
         return ret;
 }
 
@@ -137,7 +129,7 @@ static void dump_completed_IO(struct inode *inode)
 }
 
 /* Add the io_end to per-inode completed end_io list. */
-static void ext4_add_complete_io(ext4_io_end_t *io_end)
+void ext4_add_complete_io(ext4_io_end_t *io_end)
 {
         struct ext4_inode_info *ei = EXT4_I(io_end->inode);
         struct workqueue_struct *wq;
@@ -174,6 +166,8 @@ static int ext4_do_flush_completed_IO(struct inode *inode)
                 err = ext4_end_io(io);
                 if (unlikely(!ret && err))
                         ret = err;
+                io->flag &= ~EXT4_IO_END_UNWRITTEN;
+                ext4_free_io_end(io);
         }
         return ret;
 }
@@ -205,43 +199,10 @@ ext4_io_end_t *ext4_init_io_end(struct inode *inode, gfp_t flags)
                 atomic_inc(&EXT4_I(inode)->i_ioend_count);
                 io->inode = inode;
                 INIT_LIST_HEAD(&io->list);
-                atomic_set(&io->count, 1);
         }
         return io;
 }
 
-void ext4_put_io_end_defer(ext4_io_end_t *io_end)
-{
-        if (atomic_dec_and_test(&io_end->count)) {
-                if (!(io_end->flag & EXT4_IO_END_UNWRITTEN) || !io_end->size) {
-                        ext4_release_io_end(io_end);
-                        return;
-                }
-                ext4_add_complete_io(io_end);
-        }
-}
-
-int ext4_put_io_end(ext4_io_end_t *io_end)
-{
-        int err = 0;
-
-        if (atomic_dec_and_test(&io_end->count)) {
-                if (io_end->flag & EXT4_IO_END_UNWRITTEN) {
-                        err = ext4_convert_unwritten_extents(io_end->inode,
-                                                io_end->offset, io_end->size);
-                        ext4_clear_io_unwritten_flag(io_end);
-                }
-                ext4_release_io_end(io_end);
-        }
-        return err;
-}
-
-ext4_io_end_t *ext4_get_io_end(ext4_io_end_t *io_end)
-{
-        atomic_inc(&io_end->count);
-        return io_end;
-}
-
 /*
  * Print an buffer I/O error compatible with the fs/buffer.c.  This
  * provides compatibility with dmesg scrapers that look for a specific
@@ -324,7 +285,12 @@ static void ext4_end_bio(struct bio *bio, int error)
                              bi_sector >> (inode->i_blkbits - 9));
         }
 
-        ext4_put_io_end_defer(io_end);
+        if (!(io_end->flag & EXT4_IO_END_UNWRITTEN)) {
+                ext4_free_io_end(io_end);
+                return;
+        }
+
+        ext4_add_complete_io(io_end);
 }
 
 void ext4_io_submit(struct ext4_io_submit *io)
@@ -338,37 +304,40 @@ void ext4_io_submit(struct ext4_io_submit *io)
                 bio_put(io->io_bio);
         }
         io->io_bio = NULL;
-}
-
-void ext4_io_submit_init(struct ext4_io_submit *io,
-                         struct writeback_control *wbc)
-{
-        io->io_op = (wbc->sync_mode == WB_SYNC_ALL ?  WRITE_SYNC : WRITE);
-        io->io_bio = NULL;
+        io->io_op = 0;
         io->io_end = NULL;
 }
 
-static int io_submit_init_bio(struct ext4_io_submit *io,
-                              struct buffer_head *bh)
+static int io_submit_init(struct ext4_io_submit *io,
+                          struct inode *inode,
+                          struct writeback_control *wbc,
+                          struct buffer_head *bh)
 {
+        ext4_io_end_t *io_end;
+        struct page *page = bh->b_page;
         int nvecs = bio_get_nr_vecs(bh->b_bdev);
         struct bio *bio;
 
+        io_end = ext4_init_io_end(inode, GFP_NOFS);
+        if (!io_end)
+                return -ENOMEM;
         bio = bio_alloc(GFP_NOIO, min(nvecs, BIO_MAX_PAGES));
         bio->bi_sector = bh->b_blocknr * (bh->b_size >> 9);
         bio->bi_bdev = bh->b_bdev;
+        bio->bi_private = io->io_end = io_end;
         bio->bi_end_io = ext4_end_bio;
-        bio->bi_private = ext4_get_io_end(io->io_end);
-        if (!io->io_end->size)
-                io->io_end->offset = (bh->b_page->index << PAGE_CACHE_SHIFT)
-                                     + bh_offset(bh);
+
+        io_end->offset = (page->index << PAGE_CACHE_SHIFT) + bh_offset(bh);
+
         io->io_bio = bio;
+        io->io_op = (wbc->sync_mode == WB_SYNC_ALL ?  WRITE_SYNC : WRITE);
         io->io_next_block = bh->b_blocknr;
         return 0;
 }
 
 static int io_submit_add_bh(struct ext4_io_submit *io,
                             struct inode *inode,
+                            struct writeback_control *wbc,
                             struct buffer_head *bh)
 {
         ext4_io_end_t *io_end;
@@ -379,18 +348,18 @@ submit_and_retry:
                 ext4_io_submit(io);
         }
         if (io->io_bio == NULL) {
-                ret = io_submit_init_bio(io, bh);
+                ret = io_submit_init(io, inode, wbc, bh);
                 if (ret)
                         return ret;
         }
-        ret = bio_add_page(io->io_bio, bh->b_page, bh->b_size, bh_offset(bh));
-        if (ret != bh->b_size)
-                goto submit_and_retry;
         io_end = io->io_end;
         if (test_clear_buffer_uninit(bh))
                 ext4_set_io_unwritten_flag(inode, io_end);
-        io_end->size += bh->b_size;
+        io->io_end->size += bh->b_size;
         io->io_next_block++;
+        ret = bio_add_page(io->io_bio, bh->b_page, bh->b_size, bh_offset(bh));
+        if (ret != bh->b_size)
+                goto submit_and_retry;
         return 0;
 }
 
@@ -462,7 +431,7 @@ int ext4_bio_write_page(struct ext4_io_submit *io,
         do {
                 if (!buffer_async_write(bh))
                         continue;
-                ret = io_submit_add_bh(io, inode, bh);
+                ret = io_submit_add_bh(io, inode, wbc, bh);
                 if (ret) {
                         /*
                          * We only get here on ENOMEM.  Not much else