[PATCH 1/2] btrfs: Enhance btrfs_trim_fs function to handle error better

[PATCH 1/2] btrfs: Enhance btrfs_trim_fs function to handle error better

[Qu Wenruo]

Commit 93bba24d4b5ad1e5cd8b43f64e66ff9d6355dd20 upstream.

Function btrfs_trim_fs() doesn't handle errors in a consistent way. If
error happens when trimming existing block groups, it will skip the
remaining blocks and continue to trim unallocated space for each device.

The return value will only reflect the final error from device trimming.

This patch will fix such behavior by:

1) Recording the last error from block group or device trimming
   The return value will also reflect the last error during trimming.
   Make developer more aware of the problem.

2) Continuing trimming if possible
   If we failed to trim one block group or device, we could still try
   the next block group or device.

3) Report number of failures during block group and device trimming
   It would be less noisy, but still gives user a brief summary of
   what's going wrong.

Such behavior can avoid confusion for cases like failure to trim the
first block group and then only unallocated space is trimmed.

Reported-by: Chris Murphy <lists@colorremedies.com>
CC: stable@vger.kernel.org # 4.9
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ add bg_ret and dev_ret to the messages ]
Signed-off-by: David Sterba <dsterba@suse.com>
---
 fs/btrfs/extent-tree.c | 40 +++++++++++++++++++++++++++++-----------
 1 file changed, 29 insertions(+), 11 deletions(-)

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 6661116c47d9..4f28fef9dc7f 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -11124,6 +11124,10 @@ int btrfs_trim_fs(struct btrfs_root *root, struct fstrim_range *range)
 	u64 end;
 	u64 trimmed = 0;
 	u64 total_bytes = btrfs_super_total_bytes(fs_info->super_copy);
+	u64 bg_failed = 0;
+	u64 dev_failed = 0;
+	int bg_ret = 0;
+	int dev_ret = 0;
 	int ret = 0;
 
 	/*
@@ -11134,7 +11138,7 @@ int btrfs_trim_fs(struct btrfs_root *root, struct fstrim_range *range)
 	else
 		cache = btrfs_lookup_block_group(fs_info, range->start);
 
-	while (cache) {
+	for (; cache; cache = next_block_group(fs_info->tree_root, cache)) {
 		if (cache->key.objectid >= (range->start + range->len)) {
 			btrfs_put_block_group(cache);
 			break;
@@ -11148,13 +11152,15 @@ int btrfs_trim_fs(struct btrfs_root *root, struct fstrim_range *range)
 			if (!block_group_cache_done(cache)) {
 				ret = cache_block_group(cache, 0);
 				if (ret) {
-					btrfs_put_block_group(cache);
-					break;
+					bg_failed++;
+					bg_ret = ret;
+					continue;
 				}
 				ret = wait_block_group_cache_done(cache);
 				if (ret) {
-					btrfs_put_block_group(cache);
-					break;
+					bg_failed++;
+					bg_ret = ret;
+					continue;
 				}
 			}
 			ret = btrfs_trim_block_group(cache,
@@ -11165,28 +11171,40 @@ int btrfs_trim_fs(struct btrfs_root *root, struct fstrim_range *range)
 
 			trimmed += group_trimmed;
 			if (ret) {
-				btrfs_put_block_group(cache);
-				break;
+				bg_failed++;
+				bg_ret = ret;
+				continue;
 			}
 		}
-
-		cache = next_block_group(fs_info->tree_root, cache);
 	}
 
+	if (bg_failed)
+		btrfs_warn(fs_info,
+			"failed to trim %llu block group(s), last error %d",
+			bg_failed, bg_ret);
 	mutex_lock(&root->fs_info->fs_devices->device_list_mutex);
 	devices = &root->fs_info->fs_devices->alloc_list;
 	list_for_each_entry(device, devices, dev_alloc_list) {
 		ret = btrfs_trim_free_extents(device, range->minlen,
 					      &group_trimmed);
-		if (ret)
+		if (ret) {
+			dev_failed++;
+			dev_ret = ret;
 			break;
+		}
 
 		trimmed += group_trimmed;
 	}
 	mutex_unlock(&root->fs_info->fs_devices->device_list_mutex);
 
+	if (dev_failed)
+		btrfs_warn(fs_info,
+			"failed to trim %llu device(s), last error %d",
+			dev_failed, dev_ret);
 	range->len = trimmed;
-	return ret;
+	if (bg_ret)
+		return bg_ret;
+	return dev_ret;
 }
 
 /*
-- 
2.19.1

[PATCH 2/2] btrfs: Ensure btrfs_trim_fs can trim the whole filesystem

[Qu Wenruo]

Commit 6ba9fc8e628becf0e3ec94083450d089b0dec5f5 upstream.

[BUG]
fstrim on some btrfs only trims the unallocated space, not trimming any
space in existing block groups.

[CAUSE]
Before fstrim_range passed to btrfs_trim_fs(), it gets truncated to
range [0, super->total_bytes).  So later btrfs_trim_fs() will only be
able to trim block groups in range [0, super->total_bytes).

While for btrfs, any bytenr aligned to sectorsize is valid, since btrfs
uses its logical address space, there is nothing limiting the location
where we put block groups.

For filesystem with frequent balance, it's quite easy to relocate all
block groups and bytenr of block groups will start beyond
super->total_bytes.

In that case, btrfs will not trim existing block groups.

[FIX]
Just remove the truncation in btrfs_ioctl_fitrim(), so btrfs_trim_fs()
can get the unmodified range, which is normally set to [0, U64_MAX].

Reported-by: Chris Murphy <lists@colorremedies.com>
Fixes: f4c697e6406d ("btrfs: return EINVAL if start > total_bytes in fitrim ioctl")
CC: <stable@vger.kernel.org> # v4.9
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
---
 fs/btrfs/extent-tree.c | 10 +---------
 fs/btrfs/ioctl.c       | 11 +++++++----
 2 files changed, 8 insertions(+), 13 deletions(-)

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 4f28fef9dc7f..e2b8877c1a47 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -11123,21 +11123,13 @@ int btrfs_trim_fs(struct btrfs_root *root, struct fstrim_range *range)
 	u64 start;
 	u64 end;
 	u64 trimmed = 0;
-	u64 total_bytes = btrfs_super_total_bytes(fs_info->super_copy);
 	u64 bg_failed = 0;
 	u64 dev_failed = 0;
 	int bg_ret = 0;
 	int dev_ret = 0;
 	int ret = 0;
 
-	/*
-	 * try to trim all FS space, our block group may start from non-zero.
-	 */
-	if (range->len == total_bytes)
-		cache = btrfs_lookup_first_block_group(fs_info, range->start);
-	else
-		cache = btrfs_lookup_block_group(fs_info, range->start);
-
+	cache = btrfs_lookup_first_block_group(fs_info, range->start);
 	for (; cache; cache = next_block_group(fs_info->tree_root, cache)) {
 		if (cache->key.objectid >= (range->start + range->len)) {
 			btrfs_put_block_group(cache);
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index cbf512b64597..4f49132fb0b6 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -380,7 +380,6 @@ static noinline int btrfs_ioctl_fitrim(struct file *file, void __user *arg)
 	struct fstrim_range range;
 	u64 minlen = ULLONG_MAX;
 	u64 num_devices = 0;
-	u64 total_bytes = btrfs_super_total_bytes(fs_info->super_copy);
 	int ret;
 
 	if (!capable(CAP_SYS_ADMIN))
@@ -404,11 +403,15 @@ static noinline int btrfs_ioctl_fitrim(struct file *file, void __user *arg)
 		return -EOPNOTSUPP;
 	if (copy_from_user(&range, arg, sizeof(range)))
 		return -EFAULT;
-	if (range.start > total_bytes ||
-	    range.len < fs_info->sb->s_blocksize)
+
+	/*
+	 * NOTE: Don't truncate the range using super->total_bytes.  Bytenr of
+	 * block group is in the logical address space, which can be any
+	 * sectorsize aligned bytenr in  the range [0, U64_MAX].
+	 */
+	if (range.len < fs_info->sb->s_blocksize)
 		return -EINVAL;
 
-	range.len = min(range.len, total_bytes - range.start);
 	range.minlen = max(range.minlen, minlen);
 	ret = btrfs_trim_fs(fs_info->tree_root, &range);
 	if (ret < 0)
-- 
2.19.1

Re: [PATCH 1/2] btrfs: Enhance btrfs_trim_fs function to handle error better

[Greg KH]

On Mon, Nov 12, 2018 at 08:32:41AM +0800, Qu Wenruo wrote:
> Commit 93bba24d4b5ad1e5cd8b43f64e66ff9d6355dd20 upstream.
> 
> Function btrfs_trim_fs() doesn't handle errors in a consistent way. If
> error happens when trimming existing block groups, it will skip the
> remaining blocks and continue to trim unallocated space for each device.
> 
> The return value will only reflect the final error from device trimming.
> 
> This patch will fix such behavior by:
> 
> 1) Recording the last error from block group or device trimming
>    The return value will also reflect the last error during trimming.
>    Make developer more aware of the problem.
> 
> 2) Continuing trimming if possible
>    If we failed to trim one block group or device, we could still try
>    the next block group or device.
> 
> 3) Report number of failures during block group and device trimming
>    It would be less noisy, but still gives user a brief summary of
>    what's going wrong.
> 
> Such behavior can avoid confusion for cases like failure to trim the
> first block group and then only unallocated space is trimmed.
> 
> Reported-by: Chris Murphy <lists@colorremedies.com>
> CC: stable@vger.kernel.org # 4.9
> Signed-off-by: Qu Wenruo <wqu@suse.com>
> Reviewed-by: David Sterba <dsterba@suse.com>
> [ add bg_ret and dev_ret to the messages ]
> Signed-off-by: David Sterba <dsterba@suse.com>
> ---
>  fs/btrfs/extent-tree.c | 40 +++++++++++++++++++++++++++++-----------
>  1 file changed, 29 insertions(+), 11 deletions(-)

Does not apply to the latest 4.9.y tree :(

Can you please rebase and resend both of these?

thanks,

greg k-h

Re: [PATCH 1/2] btrfs: Enhance btrfs_trim_fs function to handle error better

[Qu Wenruo]

[-- Attachment #1.1: Type: text/plain, Size: 1910 bytes --]



On 2018/11/19 下午8:30, Greg KH wrote:
> On Mon, Nov 12, 2018 at 08:32:41AM +0800, Qu Wenruo wrote:
>> Commit 93bba24d4b5ad1e5cd8b43f64e66ff9d6355dd20 upstream.
>>
>> Function btrfs_trim_fs() doesn't handle errors in a consistent way. If
>> error happens when trimming existing block groups, it will skip the
>> remaining blocks and continue to trim unallocated space for each device.
>>
>> The return value will only reflect the final error from device trimming.
>>
>> This patch will fix such behavior by:
>>
>> 1) Recording the last error from block group or device trimming
>>    The return value will also reflect the last error during trimming.
>>    Make developer more aware of the problem.
>>
>> 2) Continuing trimming if possible
>>    If we failed to trim one block group or device, we could still try
>>    the next block group or device.
>>
>> 3) Report number of failures during block group and device trimming
>>    It would be less noisy, but still gives user a brief summary of
>>    what's going wrong.
>>
>> Such behavior can avoid confusion for cases like failure to trim the
>> first block group and then only unallocated space is trimmed.
>>
>> Reported-by: Chris Murphy <lists@colorremedies.com>
>> CC: stable@vger.kernel.org # 4.9
>> Signed-off-by: Qu Wenruo <wqu@suse.com>
>> Reviewed-by: David Sterba <dsterba@suse.com>
>> [ add bg_ret and dev_ret to the messages ]
>> Signed-off-by: David Sterba <dsterba@suse.com>
>> ---
>>  fs/btrfs/extent-tree.c | 40 +++++++++++++++++++++++++++++-----------
>>  1 file changed, 29 insertions(+), 11 deletions(-)
> 
> Does not apply to the latest 4.9.y tree :(

Sorry, it looks like I rebased it to the wrong branch.

Now I know which branch it should go, will send the updated patch soon.

Thanks,
Qu

> 
> Can you please rebase and resend both of these?
> 
> thanks,
> 
> greg k-h
> 


[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 488 bytes --]

[PATCH 1/2] btrfs: Enhance btrfs_trim_fs function to handle error better

[Qu Wenruo]

Commit 93bba24d4b5ad1e5cd8b43f64e66ff9d6355dd20 upstream.

Function btrfs_trim_fs() doesn't handle errors in a consistent way. If
error happens when trimming existing block groups, it will skip the
remaining blocks and continue to trim unallocated space for each device.

The return value will only reflect the final error from device trimming.

This patch will fix such behavior by:

1) Recording the last error from block group or device trimming
   The return value will also reflect the last error during trimming.
   Make developer more aware of the problem.

2) Continuing trimming if possible
   If we failed to trim one block group or device, we could still try
   the next block group or device.

3) Report number of failures during block group and device trimming
   It would be less noisy, but still gives user a brief summary of
   what's going wrong.

Such behavior can avoid confusion for cases like failure to trim the
first block group and then only unallocated space is trimmed.

Reported-by: Chris Murphy <lists@colorremedies.com>
CC: stable@vger.kernel.org # 4.9
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ add bg_ret and dev_ret to the messages ]
Signed-off-by: David Sterba <dsterba@suse.com>
[ change parameter from @fs_info to @fs_info->root for older kernel ]
---
 fs/btrfs/extent-tree.c | 53 +++++++++++++++++++++++++++++++-----------
 1 file changed, 40 insertions(+), 13 deletions(-)

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 163b61a92b59..42c4b246f749 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -11140,6 +11140,15 @@ static int btrfs_trim_free_extents(struct btrfs_device *device,
 	return ret;
 }
 
+/*
+ * Trim the whole filesystem by:
+ * 1) trimming the free space in each block group
+ * 2) trimming the unallocated space on each device
+ *
+ * This will also continue trimming even if a block group or device encounters
+ * an error.  The return value will be the last error, or 0 if nothing bad
+ * happens.
+ */
 int btrfs_trim_fs(struct btrfs_root *root, struct fstrim_range *range)
 {
 	struct btrfs_fs_info *fs_info = root->fs_info;
@@ -11151,6 +11160,10 @@ int btrfs_trim_fs(struct btrfs_root *root, struct fstrim_range *range)
 	u64 end;
 	u64 trimmed = 0;
 	u64 total_bytes = btrfs_super_total_bytes(fs_info->super_copy);
+	u64 bg_failed = 0;
+	u64 dev_failed = 0;
+	int bg_ret = 0;
+	int dev_ret = 0;
 	int ret = 0;
 
 	/*
@@ -11161,7 +11174,7 @@ int btrfs_trim_fs(struct btrfs_root *root, struct fstrim_range *range)
 	else
 		cache = btrfs_lookup_block_group(fs_info, range->start);
 
-	while (cache) {
+	for (; cache; cache = next_block_group(fs_info->tree_root, cache)) {
 		if (cache->key.objectid >= (range->start + range->len)) {
 			btrfs_put_block_group(cache);
 			break;
@@ -11175,13 +11188,15 @@ int btrfs_trim_fs(struct btrfs_root *root, struct fstrim_range *range)
 			if (!block_group_cache_done(cache)) {
 				ret = cache_block_group(cache, 0);
 				if (ret) {
-					btrfs_put_block_group(cache);
-					break;
+					bg_failed++;
+					bg_ret = ret;
+					continue;
 				}
 				ret = wait_block_group_cache_done(cache);
 				if (ret) {
-					btrfs_put_block_group(cache);
-					break;
+					bg_failed++;
+					bg_ret = ret;
+					continue;
 				}
 			}
 			ret = btrfs_trim_block_group(cache,
@@ -11192,28 +11207,40 @@ int btrfs_trim_fs(struct btrfs_root *root, struct fstrim_range *range)
 
 			trimmed += group_trimmed;
 			if (ret) {
-				btrfs_put_block_group(cache);
-				break;
+				bg_failed++;
+				bg_ret = ret;
+				continue;
 			}
 		}
-
-		cache = next_block_group(fs_info->tree_root, cache);
 	}
 
-	mutex_lock(&root->fs_info->fs_devices->device_list_mutex);
-	devices = &root->fs_info->fs_devices->devices;
+	if (bg_failed)
+		btrfs_warn(fs_info,
+			"failed to trim %llu block group(s), last error %d",
+			bg_failed, bg_ret);
+	mutex_lock(&fs_info->fs_devices->device_list_mutex);
+	devices = &fs_info->fs_devices->devices;
 	list_for_each_entry(device, devices, dev_list) {
 		ret = btrfs_trim_free_extents(device, range->minlen,
 					      &group_trimmed);
-		if (ret)
+		if (ret) {
+			dev_failed++;
+			dev_ret = ret;
 			break;
+		}
 
 		trimmed += group_trimmed;
 	}
 	mutex_unlock(&root->fs_info->fs_devices->device_list_mutex);
 
+	if (dev_failed)
+		btrfs_warn(fs_info,
+			"failed to trim %llu device(s), last error %d",
+			dev_failed, dev_ret);
 	range->len = trimmed;
-	return ret;
+	if (bg_ret)
+		return bg_ret;
+	return dev_ret;
 }
 
 /*
-- 
2.19.1