From 441c850857148935babe000fc2ba1455fe54a6a9 Mon Sep 17 00:00:00 2001 From: Curt Wohlgemuth Date: Sat, 13 Aug 2011 11:25:18 -0400 Subject: ext4: Fix ext4_should_writeback_data() for no-journal mode ext4_should_writeback_data() had an incorrect sequence of tests to determine if it should return 0 or 1: in particular, even in no-journal mode, 0 was being returned for a non-regular-file inode. This meant that, in non-journal mode, we would use ext4_journalled_aops for directories, symlinks, and other non-regular files. However, calling journalled aop callbacks when there is no valid handle, can cause problems. This would cause a kernel crash with Jan Kara's commit 2d859db3e4 ("ext4: fix data corruption in inodes with journalled data"), because we now dereference 'handle' in ext4_journalled_write_end(). I also added BUG_ONs to check for a valid handle in the obviously journal-only aops callbacks. I tested this running xfstests with a scratch device in these modes: - no-journal - data=ordered - data=writeback - data=journal All work fine; the data=journal run has many failures and a crash in xfstests 074, but this is no different from a vanilla kernel. Signed-off-by: Curt Wohlgemuth Signed-off-by: "Theodore Ts'o" Cc: stable@kernel.org --- fs/ext4/ext4_jbd2.h | 4 ++-- fs/ext4/inode.c | 4 ++++ 2 files changed, 6 insertions(+), 2 deletions(-) (limited to 'fs') diff --git a/fs/ext4/ext4_jbd2.h b/fs/ext4/ext4_jbd2.h index bb85757689b6..5802fa1dab18 100644 --- a/fs/ext4/ext4_jbd2.h +++ b/fs/ext4/ext4_jbd2.h @@ -289,10 +289,10 @@ static inline int ext4_should_order_data(struct inode *inode) static inline int ext4_should_writeback_data(struct inode *inode) { - if (!S_ISREG(inode->i_mode)) - return 0; if (EXT4_JOURNAL(inode) == NULL) return 1; + if (!S_ISREG(inode->i_mode)) + return 0; if (ext4_test_inode_flag(inode, EXT4_INODE_JOURNAL_DATA)) return 0; if (test_opt(inode->i_sb, DATA_FLAGS) == EXT4_MOUNT_WRITEBACK_DATA) diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index d47264cafee0..ad3a7ca21069 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -983,6 +983,8 @@ static int ext4_journalled_write_end(struct file *file, from = pos & (PAGE_CACHE_SIZE - 1); to = from + len; + BUG_ON(!ext4_handle_valid(handle)); + if (copied < len) { if (!PageUptodate(page)) copied = 0; @@ -1699,6 +1701,8 @@ static int __ext4_journalled_writepage(struct page *page, goto out; } + BUG_ON(!ext4_handle_valid(handle)); + ret = walk_page_buffers(handle, page_bufs, 0, len, NULL, do_journal_get_write_access); -- cgit v1.2.3 From 2581fdc810889fdea97689cb62481201d579c796 Mon Sep 17 00:00:00 2001 From: Jiaying Zhang Date: Sat, 13 Aug 2011 12:17:13 -0400 Subject: ext4: call ext4_ioend_wait and ext4_flush_completed_IO in ext4_evict_inode Flush inode's i_completed_io_list before calling ext4_io_wait to prevent the following deadlock scenario: A page fault happens while some process is writing inode A. During page fault, shrink_icache_memory is called that in turn evicts another inode B. Inode B has some pending io_end work so it calls ext4_ioend_wait() that waits for inode B's i_ioend_count to become zero. However, inode B's ioend work was queued behind some of inode A's ioend work on the same cpu's ext4-dio-unwritten workqueue. As the ext4-dio-unwritten thread on that cpu is processing inode A's ioend work, it tries to grab inode A's i_mutex lock. Since the i_mutex lock of inode A is still hold before the page fault happened, we enter a deadlock. Also moves ext4_flush_completed_IO and ext4_ioend_wait from ext4_destroy_inode() to ext4_evict_inode(). During inode deleteion, ext4_evict_inode() is called before ext4_destroy_inode() and in ext4_evict_inode(), we may call ext4_truncate() without holding i_mutex lock. As a result, there is a race between flush_completed_IO that is called from ext4_ext_truncate() and ext4_end_io_work, which may cause corruption on an io_end structure. This change moves ext4_flush_completed_IO and ext4_ioend_wait from ext4_destroy_inode() to ext4_evict_inode() to resolve the race between ext4_truncate() and ext4_end_io_work during inode deletion. Signed-off-by: Jiaying Zhang Signed-off-by: "Theodore Ts'o" Cc: stable@kernel.org --- fs/ext4/inode.c | 6 ++++++ fs/ext4/super.c | 1 - 2 files changed, 6 insertions(+), 1 deletion(-) (limited to 'fs') diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index ad3a7ca21069..7dd698107822 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -120,6 +120,12 @@ void ext4_evict_inode(struct inode *inode) int err; trace_ext4_evict_inode(inode); + + mutex_lock(&inode->i_mutex); + ext4_flush_completed_IO(inode); + mutex_unlock(&inode->i_mutex); + ext4_ioend_wait(inode); + if (inode->i_nlink) { /* * When journalling data dirty buffers are tracked only in the diff --git a/fs/ext4/super.c b/fs/ext4/super.c index 4687fea0c00f..44d0c8db2239 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -919,7 +919,6 @@ static void ext4_i_callback(struct rcu_head *head) static void ext4_destroy_inode(struct inode *inode) { - ext4_ioend_wait(inode); if (!list_empty(&(EXT4_I(inode)->i_orphan))) { ext4_msg(inode->i_sb, KERN_ERR, "Inode %lu (%p): orphan list check failed!", -- cgit v1.2.3 From 32c80b32c053dc52712dedac5e4d0aa7c93fc353 Mon Sep 17 00:00:00 2001 From: Tao Ma Date: Sat, 13 Aug 2011 12:30:59 -0400 Subject: ext4: Resolve the hang of direct i/o read in handling EXT4_IO_END_UNWRITTEN. EXT4_IO_END_UNWRITTEN flag set and the increase of i_aiodio_unwritten should be done simultaneously since ext4_end_io_nolock always clear the flag and decrease the counter in the same time. We don't increase i_aiodio_unwritten when setting EXT4_IO_END_UNWRITTEN so it will go nagative and causes some process to wait forever. Part of the patch came from Eric in his e-mail, but it doesn't fix the problem met by Michael actually. http://marc.info/?l=linux-ext4&m=131316851417460&w=2 Reported-and-Tested-by: Michael Tokarev Signed-off-by: Eric Sandeen Signed-off-by: Tao Ma Signed-off-by: "Theodore Ts'o" Cc: stable@kernel.org --- fs/ext4/inode.c | 9 ++++++++- fs/ext4/page-io.c | 6 ++++-- 2 files changed, 12 insertions(+), 3 deletions(-) (limited to 'fs') diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index 7dd698107822..762e8037c888 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -2678,8 +2678,15 @@ static void ext4_end_io_buffer_write(struct buffer_head *bh, int uptodate) goto out; } - io_end->flag = EXT4_IO_END_UNWRITTEN; + /* + * It may be over-defensive here to check EXT4_IO_END_UNWRITTEN now, + * but being more careful is always safe for the future change. + */ inode = io_end->inode; + if (!(io_end->flag & EXT4_IO_END_UNWRITTEN)) { + io_end->flag |= EXT4_IO_END_UNWRITTEN; + atomic_inc(&EXT4_I(inode)->i_aiodio_unwritten); + } /* Add the io_end to per-inode completed io list*/ spin_lock_irqsave(&EXT4_I(inode)->i_completed_io_lock, flags); diff --git a/fs/ext4/page-io.c b/fs/ext4/page-io.c index 430c401d0895..78839af7ce29 100644 --- a/fs/ext4/page-io.c +++ b/fs/ext4/page-io.c @@ -334,8 +334,10 @@ submit_and_retry: if ((io_end->num_io_pages >= MAX_IO_PAGES) && (io_end->pages[io_end->num_io_pages-1] != io_page)) goto submit_and_retry; - if (buffer_uninit(bh)) - io->io_end->flag |= EXT4_IO_END_UNWRITTEN; + if (buffer_uninit(bh) && !(io_end->flag & EXT4_IO_END_UNWRITTEN)) { + io_end->flag |= EXT4_IO_END_UNWRITTEN; + atomic_inc(&EXT4_I(inode)->i_aiodio_unwritten); + } 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)); -- cgit v1.2.3 From 9dd75f1f1a02d656a11a7b9b9e6c2759b9c1e946 Mon Sep 17 00:00:00 2001 From: Theodore Ts'o Date: Sat, 13 Aug 2011 12:58:21 -0400 Subject: ext4: fix nomblk_io_submit option so it correctly converts uninit blocks Bug discovered by Jan Kara: Finally, commit 1449032be17abb69116dbc393f67ceb8bd034f92 returned back the old IO submission code but apparently it forgot to return the old handling of uninitialized buffers so we unconditionnaly call block_write_full_page() without specifying end_io function. So AFAICS we never convert unwritten extents to written in some cases. For example when I mount the fs as: mount -t ext4 -o nomblk_io_submit,dioread_nolock /dev/ubdb /mnt and do int fd = open(argv[1], O_RDWR | O_CREAT | O_TRUNC, 0600); char buf[1024]; memset(buf, 'a', sizeof(buf)); fallocate(fd, 0, 0, 16384); write(fd, buf, sizeof(buf)); I get a file full of zeros (after remounting the filesystem so that pagecache is dropped) instead of seeing the first KB contain 'a's. Signed-off-by: "Theodore Ts'o" Cc: stable@kernel.org --- fs/ext4/inode.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) (limited to 'fs') diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index 762e8037c888..c4da98a959ae 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -1291,7 +1291,12 @@ static int mpage_da_submit_io(struct mpage_da_data *mpd, else if (test_opt(inode->i_sb, MBLK_IO_SUBMIT)) err = ext4_bio_write_page(&io_submit, page, len, mpd->wbc); - else + else if (buffer_uninit(page_bufs)) { + ext4_set_bh_endio(page_bufs, inode); + err = block_write_full_page_endio(page, + noalloc_get_block_write, + mpd->wbc, ext4_end_io_buffer_write); + } else err = block_write_full_page(page, noalloc_get_block_write, mpd->wbc); -- cgit v1.2.3 From dccaf33fa37a1bc5d651baeb3bfeb6becb86597b Mon Sep 17 00:00:00 2001 From: Jiaying Zhang Date: Fri, 19 Aug 2011 19:13:32 -0400 Subject: ext4: flush any pending end_io requests before DIO reads w/dioread_nolock There is a race between ext4 buffer write and direct_IO read with dioread_nolock mount option enabled. The problem is that we clear PageWriteback flag during end_io time but will do uninitialized-to-initialized extent conversion later with dioread_nolock. If an O_direct read request comes in during this period, ext4 will return zero instead of the recently written data. This patch checks whether there are any pending uninitialized-to-initialized extent conversion requests before doing O_direct read to close the race. Note that this is just a bandaid fix. The fundamental issue is that we clear PageWriteback flag before we really complete an IO, which is problem-prone. To fix the fundamental issue, we may need to implement an extent tree cache that we can use to look up pending to-be-converted extents. Signed-off-by: Jiaying Zhang Signed-off-by: "Theodore Ts'o" Cc: stable@kernel.org --- fs/ext4/indirect.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) (limited to 'fs') diff --git a/fs/ext4/indirect.c b/fs/ext4/indirect.c index b8602cde5b5a..0962642119c0 100644 --- a/fs/ext4/indirect.c +++ b/fs/ext4/indirect.c @@ -800,12 +800,17 @@ ssize_t ext4_ind_direct_IO(int rw, struct kiocb *iocb, } retry: - if (rw == READ && ext4_should_dioread_nolock(inode)) + if (rw == READ && ext4_should_dioread_nolock(inode)) { + if (unlikely(!list_empty(&ei->i_completed_io_list))) { + mutex_lock(&inode->i_mutex); + ext4_flush_completed_IO(inode); + mutex_unlock(&inode->i_mutex); + } ret = __blockdev_direct_IO(rw, iocb, inode, inode->i_sb->s_bdev, iov, offset, nr_segs, ext4_get_block, NULL, NULL, 0); - else { + } else { ret = blockdev_direct_IO(rw, iocb, inode, iov, offset, nr_segs, ext4_get_block); -- cgit v1.2.3