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authorLiu Bo <bo.li.liu@oracle.com>2017-11-21 22:35:40 +0100
committerDavid Sterba <dsterba@suse.com>2017-11-27 17:41:19 +0100
commitebb70442cdd4872260c2415929c456be3562da82 (patch)
tree06b3108c80b86f692d988102489882ab8bb4b711 /fs/btrfs/file.c
parentbtrfs: Fix wild memory access in compression level parser (diff)
downloadlinux-ebb70442cdd4872260c2415929c456be3562da82.tar.xz
linux-ebb70442cdd4872260c2415929c456be3562da82.zip
Btrfs: fix list_add corruption and soft lockups in fsync
Xfstests btrfs/146 revealed this corruption, [ 58.138831] Buffer I/O error on dev dm-0, logical block 2621424, async page read [ 58.151233] BTRFS error (device sdf): bdev /dev/mapper/error-test errs: wr 1, rd 0, flush 0, corrupt 0, gen 0 [ 58.152403] list_add corruption. prev->next should be next (ffff88005e6775d8), but was ffffc9000189be88. (prev=ffffc9000189be88). [ 58.153518] ------------[ cut here ]------------ [ 58.153892] WARNING: CPU: 1 PID: 1287 at lib/list_debug.c:31 __list_add_valid+0x169/0x1f0 ... [ 58.157379] RIP: 0010:__list_add_valid+0x169/0x1f0 ... [ 58.161956] Call Trace: [ 58.162264] btrfs_log_inode_parent+0x5bd/0xfb0 [btrfs] [ 58.163583] btrfs_log_dentry_safe+0x60/0x80 [btrfs] [ 58.164003] btrfs_sync_file+0x4c2/0x6f0 [btrfs] [ 58.164393] vfs_fsync_range+0x5f/0xd0 [ 58.164898] do_fsync+0x5a/0x90 [ 58.165170] SyS_fsync+0x10/0x20 [ 58.165395] entry_SYSCALL_64_fastpath+0x1f/0xbe ... It turns out that we could record btrfs_log_ctx:io_err in log_one_extents when IO fails, but make log_one_extents() return '0' instead of -EIO, so the IO error is not acknowledged by the callers, i.e. btrfs_log_inode_parent(), which would remove btrfs_log_ctx:list from list head 'root->log_ctxs'. Since btrfs_log_ctx is allocated from stack memory, it'd get freed with a object alive on the list. then a future list_add will throw the above warning. This returns the correct error in the above case. Jeff also reported this while testing against his fsync error patch set[1]. [1]: https://www.spinics.net/lists/linux-btrfs/msg65308.html "btrfs list corruption and soft lockups while testing writeback error handling" Fixes: 8407f553268a4611f254 ("Btrfs: fix data corruption after fast fsync and writeback error") Signed-off-by: Liu Bo <bo.li.liu@oracle.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
Diffstat (limited to 'fs/btrfs/file.c')
-rw-r--r--fs/btrfs/file.c5
1 files changed, 3 insertions, 2 deletions
diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index 2de7b4f4ca3c..eb1bac7c8553 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -2057,6 +2057,8 @@ int btrfs_sync_file(struct file *file, loff_t start, loff_t end, int datasync)
len = (u64)end - (u64)start + 1;
trace_btrfs_sync_file(file, datasync);
+ btrfs_init_log_ctx(&ctx, inode);
+
/*
* We write the dirty pages in the range and wait until they complete
* out of the ->i_mutex. If so, we can flush the dirty pages by
@@ -2203,8 +2205,6 @@ int btrfs_sync_file(struct file *file, loff_t start, loff_t end, int datasync)
}
trans->sync = true;
- btrfs_init_log_ctx(&ctx, inode);
-
ret = btrfs_log_dentry_safe(trans, root, dentry, start, end, &ctx);
if (ret < 0) {
/* Fallthrough and commit/free transaction. */
@@ -2262,6 +2262,7 @@ int btrfs_sync_file(struct file *file, loff_t start, loff_t end, int datasync)
ret = btrfs_end_transaction(trans);
}
out:
+ ASSERT(list_empty(&ctx.list));
err = file_check_and_advance_wb_err(file);
if (!ret)
ret = err;