Re: [PATCH v3 2/6] btrfs-progs: lowmem check: Add check for overlapping dev extents

[Su Yue]

On 10/8/18 8:30 PM, Qu Wenruo wrote:

Add such check at check_dev_item(), since at that timing we're also
iterating dev extents for dev item accounting.

Signed-off-by: Qu Wenruo 


LGTM.
Reviewed-by: Su Yue 

---
  check/mode-lowmem.c | 34 --
  1 file changed, 32 insertions(+), 2 deletions(-)

diff --git a/check/mode-lowmem.c b/check/mode-lowmem.c
index 1bce44f5658a..07c03cad77af 100644
--- a/check/mode-lowmem.c
+++ b/check/mode-lowmem.c
@@ -4065,6 +4065,8 @@ static int check_dev_item(struct btrfs_fs_info *fs_info,
u64 dev_id;
u64 used;
u64 total = 0;
+   u64 prev_devid = 0;
+   u64 prev_dev_ext_end = 0;
int ret;
  
  	dev_item = btrfs_item_ptr(eb, slot, struct btrfs_dev_item);

@@ -4086,8 +4088,16 @@ static int check_dev_item(struct btrfs_fs_info *fs_info,
return REFERENCER_MISSING;
}
  
-	/* Iterate dev_extents to calculate the used space of a device */

+   /*
+* Iterate dev_extents to calculate the used space of a device
+*
+* Also make sure no dev extents overlap and end beyond device boundary
+*/
while (1) {
+   u64 devid;
+   u64 physical_offset;
+   u64 physical_len;
+
if (path.slots[0] >= btrfs_header_nritems(path.nodes[0]))
goto next;
  
@@ -4099,7 +4109,27 @@ static int check_dev_item(struct btrfs_fs_info *fs_info,
  
  		ptr = btrfs_item_ptr(path.nodes[0], path.slots[0],

 struct btrfs_dev_extent);
-   total += btrfs_dev_extent_length(path.nodes[0], ptr);
+   devid = key.objectid;
+   physical_offset = key.offset;
+   physical_len = btrfs_dev_extent_length(path.nodes[0], ptr);
+
+   if (prev_devid == devid && physical_offset < prev_dev_ext_end) {
+   error(
+"dev extent devid %llu offset %llu len %llu overlap with previous dev extent end 
%llu",
+ devid, physical_offset, physical_len,
+ prev_dev_ext_end);
+   return ACCOUNTING_MISMATCH;
+   }
+   if (physical_offset + physical_len > total_bytes) {
+   error(
+"dev extent devid %llu offset %llu len %llu is beyond device boundary %llu",
+ devid, physical_offset, physical_len,
+ total_bytes);
+   return ACCOUNTING_MISMATCH;
+   }
+   prev_devid = devid;
+   prev_dev_ext_end = physical_offset + physical_len;
+   total += physical_len;
  next:
ret = btrfs_next_item(dev_root, );
if (ret)

[PATCH v3 2/6] btrfs-progs: lowmem check: Add check for overlapping dev extents

[Qu Wenruo]

Add such check at check_dev_item(), since at that timing we're also
iterating dev extents for dev item accounting.

Signed-off-by: Qu Wenruo 
---
 check/mode-lowmem.c | 34 --
 1 file changed, 32 insertions(+), 2 deletions(-)

diff --git a/check/mode-lowmem.c b/check/mode-lowmem.c
index 1bce44f5658a..07c03cad77af 100644
--- a/check/mode-lowmem.c
+++ b/check/mode-lowmem.c
@@ -4065,6 +4065,8 @@ static int check_dev_item(struct btrfs_fs_info *fs_info,
u64 dev_id;
u64 used;
u64 total = 0;
+   u64 prev_devid = 0;
+   u64 prev_dev_ext_end = 0;
int ret;
 
dev_item = btrfs_item_ptr(eb, slot, struct btrfs_dev_item);
@@ -4086,8 +4088,16 @@ static int check_dev_item(struct btrfs_fs_info *fs_info,
return REFERENCER_MISSING;
}
 
-   /* Iterate dev_extents to calculate the used space of a device */
+   /*
+* Iterate dev_extents to calculate the used space of a device
+*
+* Also make sure no dev extents overlap and end beyond device boundary
+*/
while (1) {
+   u64 devid;
+   u64 physical_offset;
+   u64 physical_len;
+
if (path.slots[0] >= btrfs_header_nritems(path.nodes[0]))
goto next;
 
@@ -4099,7 +4109,27 @@ static int check_dev_item(struct btrfs_fs_info *fs_info,
 
ptr = btrfs_item_ptr(path.nodes[0], path.slots[0],
 struct btrfs_dev_extent);
-   total += btrfs_dev_extent_length(path.nodes[0], ptr);
+   devid = key.objectid;
+   physical_offset = key.offset;
+   physical_len = btrfs_dev_extent_length(path.nodes[0], ptr);
+
+   if (prev_devid == devid && physical_offset < prev_dev_ext_end) {
+   error(
+"dev extent devid %llu offset %llu len %llu overlap with previous dev extent 
end %llu",
+ devid, physical_offset, physical_len,
+ prev_dev_ext_end);
+   return ACCOUNTING_MISMATCH;
+   }
+   if (physical_offset + physical_len > total_bytes) {
+   error(
+"dev extent devid %llu offset %llu len %llu is beyond device boundary %llu",
+ devid, physical_offset, physical_len,
+ total_bytes);
+   return ACCOUNTING_MISMATCH;
+   }
+   prev_devid = devid;
+   prev_dev_ext_end = physical_offset + physical_len;
+   total += physical_len;
 next:
ret = btrfs_next_item(dev_root, );
if (ret)
-- 
2.19.1