Re: [PATCH 1/2] btrfs: remove old tree_root dirent processing in btrfs_real_readdir()

[David Sterba]

On Mon, Nov 14, 2016 at 09:08:14PM -0500, Jeff Mahoney wrote:
> >> -   */
> >> -  if (location.type == BTRFS_ROOT_ITEM_KEY &&
> >> -  location.objectid == root->root_key.objectid) {
> >> -  over = 0;
> >> -  goto skip;
> >> -  }
> >> -  over = !dir_emit(ctx, name_ptr, name_len,
> >> - location.objectid, d_type);
> >> +  over = !dir_emit(ctx, name_ptr, name_len, location.objectid,
> >> +   d_type);
> >>  
> >> -skip:
> >> -  if (name_ptr != tmp_name)
> >> -  kfree(name_ptr);
> >> +  if (name_ptr != tmp_name)
> >> +  kfree(name_ptr);
> >>  
> >> -  if (over)
> >> -  goto nopos;
> >> -  emitted = true;
> > 
> > Shouldn't this line (getting rid of emitted) be in the next patch?
> 
> Yep.  Good catch.

Updated.
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Re: [PATCH 1/2] btrfs: remove old tree_root dirent processing in btrfs_real_readdir()

[Jeff Mahoney]

On 11/11/16 11:05 AM, Omar Sandoval wrote:
> On Sat, Nov 05, 2016 at 01:26:34PM -0400, je...@suse.com wrote:
>> From: Jeff Mahoney 
>>
>> Commit 3de4586c527 (Btrfs: Allow subvolumes and snapshots anywhere
>> in the directory tree) introduced the current system of placing
>> snapshots in the directory tree.  It also introduced the behavior of
>> creating the snapshot and then creating the directory entries for it.
>>
>> We've kept this code around for compatibility reasons, but it turns
>> out that no file systems with the old tree_root based snapshots can
>> be mounted on newer (>= 2009) kernels anyway.  About a month after the
>> above commit, commit 2a7108ad89e (Btrfs: rev the disk format for the
>> inode compat and csum selection changes) landed, changing the superblock
>> magic number.
>>
>> As a result, we know that we'll never encounter tree_root-based dirents
>> or have to deal with skipping our own snapshot dirents.  Since that
>> also means that we're now only iterating over DIR_INDEX items, which only
>> contain one directory entry per leaf item, we don't need to loop over
>> the leaf item contents anymore either.
>>
>> Signed-off-by: Jeff Mahoney 
> 
> Hi, Jeff,

Hi Omar -

> One comment below.
> 
>> ---
>>  fs/btrfs/inode.c | 118 
>> +--
>>  1 file changed, 37 insertions(+), 81 deletions(-)
>>
>> diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
>> index 2b790bd..c52239d 100644
>> --- a/fs/btrfs/inode.c
>> +++ b/fs/btrfs/inode.c
>> @@ -5805,20 +5805,13 @@ static int btrfs_real_readdir(struct file *file, 
>> struct dir_context *ctx)
>>  int slot;
>>  unsigned char d_type;
>>  int over = 0;
>> -u32 di_cur;
>> -u32 di_total;
>> -u32 di_len;
>> -int key_type = BTRFS_DIR_INDEX_KEY;
>>  char tmp_name[32];
>>  char *name_ptr;
>>  int name_len;
>>  int is_curr = 0;/* ctx->pos points to the current index? */
>>  bool emitted;
>>  bool put = false;
>> -
>> -/* FIXME, use a real flag for deciding about the key type */
>> -if (root->fs_info->tree_root == root)
>> -key_type = BTRFS_DIR_ITEM_KEY;
>> +struct btrfs_key location;
>>  
>>  if (!dir_emit_dots(file, ctx))
>>  return 0;
>> @@ -5829,14 +5822,11 @@ static int btrfs_real_readdir(struct file *file, 
>> struct dir_context *ctx)
>>  
>>  path->reada = READA_FORWARD;
>>  
>> -if (key_type == BTRFS_DIR_INDEX_KEY) {
>> -INIT_LIST_HEAD(_list);
>> -INIT_LIST_HEAD(_list);
>> -put = btrfs_readdir_get_delayed_items(inode, _list,
>> -  _list);
>> -}
>> +INIT_LIST_HEAD(_list);
>> +INIT_LIST_HEAD(_list);
>> +put = btrfs_readdir_get_delayed_items(inode, _list, _list);
>>  
>> -key.type = key_type;
>> +key.type = BTRFS_DIR_INDEX_KEY;
>>  key.offset = ctx->pos;
>>  key.objectid = btrfs_ino(inode);
>>  
>> @@ -5862,85 +5852,53 @@ static int btrfs_real_readdir(struct file *file, 
>> struct dir_context *ctx)
>>  
>>  if (found_key.objectid != key.objectid)
>>  break;
>> -if (found_key.type != key_type)
>> +if (found_key.type != BTRFS_DIR_INDEX_KEY)
>>  break;
>>  if (found_key.offset < ctx->pos)
>>  goto next;
>> -if (key_type == BTRFS_DIR_INDEX_KEY &&
>> -btrfs_should_delete_dir_index(_list,
>> -  found_key.offset))
>> +if (btrfs_should_delete_dir_index(_list, found_key.offset))
>>  goto next;
>>  
>>  ctx->pos = found_key.offset;
>>  is_curr = 1;
>>  
>>  di = btrfs_item_ptr(leaf, slot, struct btrfs_dir_item);
>> -di_cur = 0;
>> -di_total = btrfs_item_size(leaf, item);
>> -
>> -while (di_cur < di_total) {
>> -struct btrfs_key location;
>> -
>> -if (verify_dir_item(root, leaf, di))
>> -break;
>> +if (verify_dir_item(root, leaf, di))
>> +goto next;
>>  
>> -name_len = btrfs_dir_name_len(leaf, di);
>> -if (name_len <= sizeof(tmp_name)) {
>> -name_ptr = tmp_name;
>> -} else {
>> -name_ptr = kmalloc(name_len, GFP_KERNEL);
>> -if (!name_ptr) {
>> -ret = -ENOMEM;
>> -goto err;
>> -}
>> +name_len = btrfs_dir_name_len(leaf, di);
>> +if (name_len <= sizeof(tmp_name)) {
>> +name_ptr = tmp_name;
>> +} else {
>> +name_ptr = kmalloc(name_len, GFP_KERNEL);
>> +if 

Re: [PATCH 1/2] btrfs: remove old tree_root dirent processing in btrfs_real_readdir()

[Omar Sandoval]

On Sat, Nov 05, 2016 at 01:26:34PM -0400, je...@suse.com wrote:
> From: Jeff Mahoney 
> 
> Commit 3de4586c527 (Btrfs: Allow subvolumes and snapshots anywhere
> in the directory tree) introduced the current system of placing
> snapshots in the directory tree.  It also introduced the behavior of
> creating the snapshot and then creating the directory entries for it.
> 
> We've kept this code around for compatibility reasons, but it turns
> out that no file systems with the old tree_root based snapshots can
> be mounted on newer (>= 2009) kernels anyway.  About a month after the
> above commit, commit 2a7108ad89e (Btrfs: rev the disk format for the
> inode compat and csum selection changes) landed, changing the superblock
> magic number.
> 
> As a result, we know that we'll never encounter tree_root-based dirents
> or have to deal with skipping our own snapshot dirents.  Since that
> also means that we're now only iterating over DIR_INDEX items, which only
> contain one directory entry per leaf item, we don't need to loop over
> the leaf item contents anymore either.
> 
> Signed-off-by: Jeff Mahoney 

Hi, Jeff,

One comment below.

> ---
>  fs/btrfs/inode.c | 118 
> +--
>  1 file changed, 37 insertions(+), 81 deletions(-)
> 
> diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
> index 2b790bd..c52239d 100644
> --- a/fs/btrfs/inode.c
> +++ b/fs/btrfs/inode.c
> @@ -5805,20 +5805,13 @@ static int btrfs_real_readdir(struct file *file, 
> struct dir_context *ctx)
>   int slot;
>   unsigned char d_type;
>   int over = 0;
> - u32 di_cur;
> - u32 di_total;
> - u32 di_len;
> - int key_type = BTRFS_DIR_INDEX_KEY;
>   char tmp_name[32];
>   char *name_ptr;
>   int name_len;
>   int is_curr = 0;/* ctx->pos points to the current index? */
>   bool emitted;
>   bool put = false;
> -
> - /* FIXME, use a real flag for deciding about the key type */
> - if (root->fs_info->tree_root == root)
> - key_type = BTRFS_DIR_ITEM_KEY;
> + struct btrfs_key location;
>  
>   if (!dir_emit_dots(file, ctx))
>   return 0;
> @@ -5829,14 +5822,11 @@ static int btrfs_real_readdir(struct file *file, 
> struct dir_context *ctx)
>  
>   path->reada = READA_FORWARD;
>  
> - if (key_type == BTRFS_DIR_INDEX_KEY) {
> - INIT_LIST_HEAD(_list);
> - INIT_LIST_HEAD(_list);
> - put = btrfs_readdir_get_delayed_items(inode, _list,
> -   _list);
> - }
> + INIT_LIST_HEAD(_list);
> + INIT_LIST_HEAD(_list);
> + put = btrfs_readdir_get_delayed_items(inode, _list, _list);
>  
> - key.type = key_type;
> + key.type = BTRFS_DIR_INDEX_KEY;
>   key.offset = ctx->pos;
>   key.objectid = btrfs_ino(inode);
>  
> @@ -5862,85 +5852,53 @@ static int btrfs_real_readdir(struct file *file, 
> struct dir_context *ctx)
>  
>   if (found_key.objectid != key.objectid)
>   break;
> - if (found_key.type != key_type)
> + if (found_key.type != BTRFS_DIR_INDEX_KEY)
>   break;
>   if (found_key.offset < ctx->pos)
>   goto next;
> - if (key_type == BTRFS_DIR_INDEX_KEY &&
> - btrfs_should_delete_dir_index(_list,
> -   found_key.offset))
> + if (btrfs_should_delete_dir_index(_list, found_key.offset))
>   goto next;
>  
>   ctx->pos = found_key.offset;
>   is_curr = 1;
>  
>   di = btrfs_item_ptr(leaf, slot, struct btrfs_dir_item);
> - di_cur = 0;
> - di_total = btrfs_item_size(leaf, item);
> -
> - while (di_cur < di_total) {
> - struct btrfs_key location;
> -
> - if (verify_dir_item(root, leaf, di))
> - break;
> + if (verify_dir_item(root, leaf, di))
> + goto next;
>  
> - name_len = btrfs_dir_name_len(leaf, di);
> - if (name_len <= sizeof(tmp_name)) {
> - name_ptr = tmp_name;
> - } else {
> - name_ptr = kmalloc(name_len, GFP_KERNEL);
> - if (!name_ptr) {
> - ret = -ENOMEM;
> - goto err;
> - }
> + name_len = btrfs_dir_name_len(leaf, di);
> + if (name_len <= sizeof(tmp_name)) {
> + name_ptr = tmp_name;
> + } else {
> + name_ptr = kmalloc(name_len, GFP_KERNEL);
> + if (!name_ptr) {
> + ret = -ENOMEM;
> + goto err;
>

Re: [PATCH 1/2] btrfs: remove old tree_root dirent processing in btrfs_real_readdir()

[David Sterba]

On Sat, Nov 05, 2016 at 01:26:34PM -0400, je...@suse.com wrote:
> From: Jeff Mahoney 
> 
> Commit 3de4586c527 (Btrfs: Allow subvolumes and snapshots anywhere
> in the directory tree) introduced the current system of placing
> snapshots in the directory tree.  It also introduced the behavior of
> creating the snapshot and then creating the directory entries for it.
> 
> We've kept this code around for compatibility reasons, but it turns
> out that no file systems with the old tree_root based snapshots can
> be mounted on newer (>= 2009) kernels anyway.  About a month after the
> above commit, commit 2a7108ad89e (Btrfs: rev the disk format for the
> inode compat and csum selection changes) landed, changing the superblock
> magic number.
> 
> As a result, we know that we'll never encounter tree_root-based dirents
> or have to deal with skipping our own snapshot dirents.  Since that
> also means that we're now only iterating over DIR_INDEX items, which only
> contain one directory entry per leaf item, we don't need to loop over
> the leaf item contents anymore either.
> 
> Signed-off-by: Jeff Mahoney 

Reviewed-by: David Sterba 
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[PATCH 1/2] btrfs: remove old tree_root dirent processing in btrfs_real_readdir()

[jeffm]

From: Jeff Mahoney 

Commit 3de4586c527 (Btrfs: Allow subvolumes and snapshots anywhere
in the directory tree) introduced the current system of placing
snapshots in the directory tree.  It also introduced the behavior of
creating the snapshot and then creating the directory entries for it.

We've kept this code around for compatibility reasons, but it turns
out that no file systems with the old tree_root based snapshots can
be mounted on newer (>= 2009) kernels anyway.  About a month after the
above commit, commit 2a7108ad89e (Btrfs: rev the disk format for the
inode compat and csum selection changes) landed, changing the superblock
magic number.

As a result, we know that we'll never encounter tree_root-based dirents
or have to deal with skipping our own snapshot dirents.  Since that
also means that we're now only iterating over DIR_INDEX items, which only
contain one directory entry per leaf item, we don't need to loop over
the leaf item contents anymore either.

Signed-off-by: Jeff Mahoney 
---
 fs/btrfs/inode.c | 118 +--
 1 file changed, 37 insertions(+), 81 deletions(-)

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 2b790bd..c52239d 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -5805,20 +5805,13 @@ static int btrfs_real_readdir(struct file *file, struct 
dir_context *ctx)
int slot;
unsigned char d_type;
int over = 0;
-   u32 di_cur;
-   u32 di_total;
-   u32 di_len;
-   int key_type = BTRFS_DIR_INDEX_KEY;
char tmp_name[32];
char *name_ptr;
int name_len;
int is_curr = 0;/* ctx->pos points to the current index? */
bool emitted;
bool put = false;
-
-   /* FIXME, use a real flag for deciding about the key type */
-   if (root->fs_info->tree_root == root)
-   key_type = BTRFS_DIR_ITEM_KEY;
+   struct btrfs_key location;
 
if (!dir_emit_dots(file, ctx))
return 0;
@@ -5829,14 +5822,11 @@ static int btrfs_real_readdir(struct file *file, struct 
dir_context *ctx)
 
path->reada = READA_FORWARD;
 
-   if (key_type == BTRFS_DIR_INDEX_KEY) {
-   INIT_LIST_HEAD(_list);
-   INIT_LIST_HEAD(_list);
-   put = btrfs_readdir_get_delayed_items(inode, _list,
- _list);
-   }
+   INIT_LIST_HEAD(_list);
+   INIT_LIST_HEAD(_list);
+   put = btrfs_readdir_get_delayed_items(inode, _list, _list);
 
-   key.type = key_type;
+   key.type = BTRFS_DIR_INDEX_KEY;
key.offset = ctx->pos;
key.objectid = btrfs_ino(inode);
 
@@ -5862,85 +5852,53 @@ static int btrfs_real_readdir(struct file *file, struct 
dir_context *ctx)
 
if (found_key.objectid != key.objectid)
break;
-   if (found_key.type != key_type)
+   if (found_key.type != BTRFS_DIR_INDEX_KEY)
break;
if (found_key.offset < ctx->pos)
goto next;
-   if (key_type == BTRFS_DIR_INDEX_KEY &&
-   btrfs_should_delete_dir_index(_list,
- found_key.offset))
+   if (btrfs_should_delete_dir_index(_list, found_key.offset))
goto next;
 
ctx->pos = found_key.offset;
is_curr = 1;
 
di = btrfs_item_ptr(leaf, slot, struct btrfs_dir_item);
-   di_cur = 0;
-   di_total = btrfs_item_size(leaf, item);
-
-   while (di_cur < di_total) {
-   struct btrfs_key location;
-
-   if (verify_dir_item(root, leaf, di))
-   break;
+   if (verify_dir_item(root, leaf, di))
+   goto next;
 
-   name_len = btrfs_dir_name_len(leaf, di);
-   if (name_len <= sizeof(tmp_name)) {
-   name_ptr = tmp_name;
-   } else {
-   name_ptr = kmalloc(name_len, GFP_KERNEL);
-   if (!name_ptr) {
-   ret = -ENOMEM;
-   goto err;
-   }
+   name_len = btrfs_dir_name_len(leaf, di);
+   if (name_len <= sizeof(tmp_name)) {
+   name_ptr = tmp_name;
+   } else {
+   name_ptr = kmalloc(name_len, GFP_KERNEL);
+   if (!name_ptr) {
+   ret = -ENOMEM;
+   goto err;
}
-   read_extent_buffer(leaf, name_ptr,
-  (unsigned long)(di + 1), name_len);
-
-   d_type =