Btrfs: fix space leak when skipping small extents during trimming
PATCH 1/2 Btrfs: fix space leak when skipping small extents during trimming
We're taking a free space extent out of the free space cache, trimming it and then putting it back into the cache.
However for an extent that is smaller than the specified minimum length, it's taken out but won't be put back, which causes space leak.
Signed-off-by Li Zefan <[email protected]>
---
Unfortunately I have no trim-able device to test the patch.
--- fs/btrfs/free-space-cache.c | 34 +++++++++++++++++----------------- 1 files changed, 17 insertions(+), 17 deletions(-)
fs/btrfs/free-space-cache.c +17 -17
@@ -2460,6 +2460,7 @@ int btrfs_trim_block_group(struct btrfs_block_group_cache *block_group,u64 bytes =0 ;u64 actually_trimmed;int ret =0 ; +int update_ret; *trimmed =0 ;
@@ -2483,6 +2484,7 @@ int btrfs_trim_block_group(struct btrfs_block_group_cache *block_group, }if (entry->bitmap) { + bytes =0 ; ret =search_bitmap (ctl, entry, &start, &bytes);if (!ret) {if (start >= end) {
@@ -2490,6 +2492,8 @@ int btrfs_trim_block_group(struct btrfs_block_group_cache *block_group,break ; } bytes =min (bytes, end - start); +if (bytes < minlen) + goto next;bitmap_clear_bits (ctl, entry, start, bytes);if (entry->bytes ==0 )free_bitmap (ctl, entry);
@@ -2503,33 +2507,29 @@ int btrfs_trim_block_group(struct btrfs_block_group_cache *block_group, }else { start = entry->offset; bytes =min (entry->bytes, end - start); +if (bytes < minlen) + goto next;unlink_free_space (ctl, entry);kmem_cache_free (btrfs_free_space_cachep, entry); }spin_unlock (&ctl->tree_lock); -if (bytes >= minlen) { -int update_ret; - update_ret =btrfs_update_reserved_bytes (block_group, - bytes,1 ,1 ); + update_ret =btrfs_update_reserved_bytes (block_group, + bytes,1 ,1 ); - ret =btrfs_error_discard_extent (fs_info->extent_root, - start, - bytes, - &actually_trimmed); + ret =btrfs_error_discard_extent (fs_info->extent_root, start, + bytes, &actually_trimmed); -btrfs_add_free_space (block_group, start, bytes); -if (!update_ret) -btrfs_update_reserved_bytes (block_group, - bytes,0 ,1 ); +btrfs_add_free_space (block_group, start, bytes); +if (!update_ret) +btrfs_update_reserved_bytes (block_group, bytes,0 ,1 ); -if (ret) -break ; - *trimmed += actually_trimmed; - } +if (ret) +break ; + *trimmed += actually_trimmed; +next: start += bytes; - bytes =0 ;if (fatal_signal_pending (current)) { ret = -ERESTARTSYS ;
PATCH 2/2 Btrfs: fix space leak when trimming free extents
When the end of an extent exceeds the end of the specified range, the extent will be accidentally truncated.
Signed-off-by Li Zefan <[email protected]>
--- fs/btrfs/free-space-cache.c | 9 ++++++++- 1 files changed, 8 insertions(+), 1 deletions(-)
fs/btrfs/free-space-cache.c +8 -1
@@ -2509,8 +2509,15 @@ int btrfs_trim_block_group(struct btrfs_block_group_cache *block_group, bytes =min (entry->bytes, end - start);if (bytes < minlen) goto next; +unlink_free_space (ctl, entry); -kmem_cache_free (btrfs_free_space_cachep, entry); +if (bytes < entry->bytes) { + entry->offset = entry->offset + bytes; + entry->bytes = entry->bytes - bytes; +link_free_space (ctl, entry); + }else { +kmem_cache_free (btrfs_free_space_cachep, entry); + } }spin_unlock (&ctl->tree_lock);
-- 1.7.3.1
Re: [PATCH 2/2] Btrfs: fix space leak when trimming free extents
Quoted 13 lines · Li Zefan
When the end of an extent exceeds the end of the specified range, the extent will be accidentally truncated.
Signed-off-by Li Zefan <[email protected]>--- fs/btrfs/free-space-cache.c | 9 ++++++++- 1 files changed, 8 insertions(+), 1 deletions(-)fs/btrfs/free-space-cache.c +0
-0
fs/btrfs/free-space-cache.c int btrfs_trim_block_group(struct btrfs_block_group_cache *block_group, · line 2517
Quoted 10 lines
fs/btrfs/free-space-cache.c +5
-1@@ -2509,8 +2509,15 @@ int btrfs_trim_block_group(struct btrfs_block_group_cache *block_group, bytes =min (entry->bytes, end - start);if (bytes < minlen) goto next; +unlink_free_space (ctl, entry); -kmem_cache_free (btrfs_free_space_cachep, entry); +if (bytes < entry->bytes) { + entry->offset = entry->offset + bytes; + entry->bytes = entry->bytes - bytes; +link_free_space (ctl, entry);
yes, I forgot to link the rest extent to the free space cache. Thanks for the fix!
Quoted 8 lines
fs/btrfs/free-space-cache.c +3
-1+ }else { +kmem_cache_free (btrfs_free_space_cachep, entry); + } }spin_unlock (&ctl->tree_lock); -- 1.7.3.1
Quoted 3 lines · Li Zefan
We're taking a free space extent out of the free space cache, trimming it and then putting it back into the cache.
sorry for the late reply, I can hardly to find time look at this.
Quoted 2 lines
However for an extent that is smaller than the specified minimum length, it's taken out but won't be put back, which causes space leak.
yes, you are correct, and the fix looks good to me, Thanks
Quoted 87 lines
Signed-off-by Li Zefan <[email protected]>---
Unfortunately I have no trim-able device to test the patch.
--- fs/btrfs/free-space-cache.c | 34 +++++++++++++++++----------------- 1 files changed, 17 insertions(+), 17 deletions(-)fs/btrfs/free-space-cache.c +17
-17@@ -2460,6 +2460,7 @@ int btrfs_trim_block_group(struct btrfs_block_group_cache *block_group,u64 bytes =0 ;u64 actually_trimmed;int ret =0 ; +int update_ret; *trimmed =0 ;@@ -2483,6 +2484,7 @@ int btrfs_trim_block_group(struct btrfs_block_group_cache *block_group, }if (entry->bitmap) { + bytes =0 ; ret =search_bitmap (ctl, entry, &start, &bytes);if (!ret) {if (start >= end) {@@ -2490,6 +2492,8 @@ int btrfs_trim_block_group(struct btrfs_block_group_cache *block_group,break ; } bytes =min (bytes, end - start); +if (bytes < minlen) + goto next;bitmap_clear_bits (ctl, entry, start, bytes);if (entry->bytes ==0 )free_bitmap (ctl, entry);@@ -2503,33 +2507,29 @@ int btrfs_trim_block_group(struct btrfs_block_group_cache *block_group, }else { start = entry->offset; bytes =min (entry->bytes, end - start); +if (bytes < minlen) + goto next;unlink_free_space (ctl, entry);kmem_cache_free (btrfs_free_space_cachep, entry); }spin_unlock (&ctl->tree_lock); -if (bytes >= minlen) { -int update_ret; - update_ret =btrfs_update_reserved_bytes (block_group, - bytes,1 ,1 ); + update_ret =btrfs_update_reserved_bytes (block_group, + bytes,1 ,1 ); - ret =btrfs_error_discard_extent (fs_info->extent_root, - start, - bytes, - &actually_trimmed); + ret =btrfs_error_discard_extent (fs_info->extent_root, start, + bytes, &actually_trimmed); -btrfs_add_free_space (block_group, start, bytes); -if (!update_ret) -btrfs_update_reserved_bytes (block_group, - bytes,0 ,1 ); +btrfs_add_free_space (block_group, start, bytes); +if (!update_ret) +btrfs_update_reserved_bytes (block_group, bytes,0 ,1 ); -if (ret) -break ; - *trimmed += actually_trimmed; - } +if (ret) +break ; + *trimmed += actually_trimmed; +next: start += bytes; - bytes =0 ;if (fatal_signal_pending (current)) { ret = -ERESTARTSYS ;