From 401b41e5a85a635fd9888ba8969c5006a5dbd399 Mon Sep 17 00:00:00 2001 From: Anand Jain Date: Sat, 6 May 2017 07:17:54 +0800 Subject: [PATCH] btrfs: add framework to handle device flush error as a volume This adds comments to the flush error handling part of the code, and hopes to maintain the same logic with a framework which can be used to handle the errors at the volume level. Signed-off-by: Anand Jain Reviewed-by: David Sterba Signed-off-by: David Sterba --- fs/btrfs/disk-io.c | 57 ++++++++++++++++++++++++++++++++++++++++++---- fs/btrfs/volumes.h | 1 + 2 files changed, 54 insertions(+), 4 deletions(-) diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index 5f678dcb20e6..bafdd2fe8f88 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -3509,6 +3509,10 @@ static int write_dev_flush(struct btrfs_device *device, int wait) if (wait) { bio = device->flush_bio; if (!bio) + /* + * This means the alloc has failed with ENOMEM, however + * here we return 0, as its not a device error. + */ return 0; wait_for_completion(&device->flush_wait); @@ -3548,6 +3552,32 @@ static int write_dev_flush(struct btrfs_device *device, int wait) return 0; } +static int check_barrier_error(struct btrfs_fs_devices *fsdevs) +{ + int submit_flush_error = 0; + int dev_flush_error = 0; + struct btrfs_device *dev; + int tolerance; + + list_for_each_entry_rcu(dev, &fsdevs->devices, dev_list) { + if (!dev->bdev) { + submit_flush_error++; + dev_flush_error++; + continue; + } + if (dev->last_flush_error == -ENOMEM) + submit_flush_error++; + if (dev->last_flush_error && dev->last_flush_error != -ENOMEM) + dev_flush_error++; + } + + tolerance = fsdevs->fs_info->num_tolerated_disk_barrier_failures; + if (submit_flush_error > tolerance || dev_flush_error > tolerance) + return -EIO; + + return 0; +} + /* * send an empty flush down to each device in parallel, * then wait for them @@ -3575,6 +3605,7 @@ static int barrier_all_devices(struct btrfs_fs_info *info) ret = write_dev_flush(dev, 0); if (ret) errors_send++; + dev->last_flush_error = ret; } /* wait for all the barriers */ @@ -3589,12 +3620,30 @@ static int barrier_all_devices(struct btrfs_fs_info *info) continue; ret = write_dev_flush(dev, 1); - if (ret) + if (ret) { + dev->last_flush_error = ret; errors_wait++; + } + } + + /* + * Try hard in case of flush. Lets say, in RAID1 we have + * the following situation + * dev1: EIO dev2: ENOMEM + * this is not a fatal error as we hope to recover from + * ENOMEM in the next attempt to flush. + * But the following is considered as fatal + * dev1: ENOMEM dev2: ENOMEM + * dev1: bdev == NULL dev2: ENOMEM + */ + if (errors_send || errors_wait) { + /* + * At some point we need the status of all disks + * to arrive at the volume status. So error checking + * is being pushed to a separate loop. + */ + return check_barrier_error(info->fs_devices); } - if (errors_send > info->num_tolerated_disk_barrier_failures || - errors_wait > info->num_tolerated_disk_barrier_failures) - return -EIO; return 0; } diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h index c7d0fbc915ca..094521729df1 100644 --- a/fs/btrfs/volumes.h +++ b/fs/btrfs/volumes.h @@ -74,6 +74,7 @@ struct btrfs_device { int missing; int can_discard; int is_tgtdev_for_dev_replace; + int last_flush_error; #ifdef __BTRFS_NEED_DEVICE_DATA_ORDERED seqcount_t data_seqcount; -- 2.20.1