[PREVIEW] [PATCH 4/4] staging: erofs: add error handling for xattr submodule
Chao Yu
yuchao0 at huawei.com
Fri Aug 10 16:08:46 AEST 2018
Hi Xiang,
On 2018/8/10 11:47, Gao Xiang wrote:
> Hi Chao,
>
> On 2018/8/10 11:40, Chao Yu wrote:
>> On 2018/8/1 14:01, Gao Xiang wrote:
>>> This patch enhances the missing error handling code for
>>> xattr submodule, which improves the stability for the rare cases.
>>>
>>> Signed-off-by: Gao Xiang <gaoxiang25 at huawei.com>
>>> ---
>>> drivers/staging/erofs/xattr.c | 114 ++++++++++++++++++++++++++++--------------
>>> 1 file changed, 77 insertions(+), 37 deletions(-)
>>>
>>> diff --git a/drivers/staging/erofs/xattr.c b/drivers/staging/erofs/xattr.c
>>> index 702434b..bd911bb 100644
>>> --- a/drivers/staging/erofs/xattr.c
>>> +++ b/drivers/staging/erofs/xattr.c
>>> @@ -24,16 +24,25 @@ struct xattr_iter {
>>>
>>> static inline void xattr_iter_end(struct xattr_iter *it, bool atomic)
>>> {
>>> - /* only init_inode_xattrs use non-atomic once */
>>> + /* the only user of kunmap() is 'init_inode_xattrs' */
>>> if (unlikely(!atomic))
>>> kunmap(it->page);
>>> else
>>> kunmap_atomic(it->kaddr);
>>> +
>>> unlock_page(it->page);
>>> put_page(it->page);
>>> }
>>>
>>> -static void init_inode_xattrs(struct inode *inode)
>>> +static inline void xattr_iter_end_final(struct xattr_iter *it)
>>> +{
>>> + if (unlikely(it->page == NULL))
>>> + return;
>>> +
>>> + xattr_iter_end(it, true);
>>> +}
>>> +
>>> +static int init_inode_xattrs(struct inode *inode)
>>> {
>>> struct xattr_iter it;
>>> unsigned i;
>>> @@ -44,7 +53,7 @@ static void init_inode_xattrs(struct inode *inode)
>>> bool atomic_map;
>>>
>>> if (likely(inode_has_inited_xattr(inode)))
>>> - return;
>>> + return 0;
>>>
>>> vi = EROFS_V(inode);
>>> BUG_ON(!vi->xattr_isize);
>>> @@ -55,7 +64,8 @@ static void init_inode_xattrs(struct inode *inode)
>>> it.ofs = erofs_blkoff(iloc(sbi, vi->nid) + vi->inode_isize);
>>>
>>> it.page = erofs_get_inline_page_nofail(inode, it.blkaddr);
>>
>> Need to introduce and use erofs_get_inline_page()?
>>
>>> - BUG_ON(IS_ERR(it.page));
>>> + if (unlikely(IS_ERR(it.page)))
>>> + return PTR_ERR(it.page);
>>>
>>> /* read in shared xattr array (non-atomic, see kmalloc below) */
>>> it.kaddr = kmap(it.page);
>>> @@ -64,9 +74,12 @@ static void init_inode_xattrs(struct inode *inode)
>>> ih = (struct erofs_xattr_ibody_header *)(it.kaddr + it.ofs);
>>>
>>> vi->xattr_shared_count = ih->h_shared_count;
>>> - vi->xattr_shared_xattrs = (unsigned *)kmalloc_array(
>>> - vi->xattr_shared_count, sizeof(unsigned),
>>> - GFP_KERNEL | __GFP_NOFAIL);
>>> + vi->xattr_shared_xattrs = kmalloc_array(vi->xattr_shared_count,
>>> + sizeof(unsigned), GFP_KERNEL);
>>> + if (unlikely(vi->xattr_shared_xattrs == NULL)) {
>>> + xattr_iter_end(&it, atomic_map);
>>> + return -ENOMEM;
>>> + }
>>>
>>> /* let's skip ibody header */
>>> it.ofs += sizeof(struct erofs_xattr_ibody_header);
>>> @@ -79,7 +92,8 @@ static void init_inode_xattrs(struct inode *inode)
>>>
>>> it.page = erofs_get_meta_page_nofail(sb,
>>> ++it.blkaddr, S_ISDIR(inode->i_mode));
>>
>> Need to use erofs_get_meta_page() instead?
>>
>> Thanks,
>
> My consideration is for example,
>
> init_inode_xattrs itself can be seen as a part of inode initialization (other fs does it in
> inode initialization, but erofs does it in the first xattr request), if it fail, the only way
> is to retry again...but with more overhead to retry...
I think we can easily return an error to user no matter we encounter -ENOMEM or
-EIO, so erofs_get_meta_page() is enough here, thoughts?
Thanks,
>
> How do you think about it? ...
>
>>
>>> - BUG_ON(IS_ERR(it.page));
>>> + if (unlikely(IS_ERR(it.page)))
>>> + return PTR_ERR(it.page);
>>>
>>> it.kaddr = kmap_atomic(it.page);
>>> atomic_map = true;
>>> @@ -92,6 +106,7 @@ static void init_inode_xattrs(struct inode *inode)
>>> xattr_iter_end(&it, atomic_map);
>>>
>>> inode_set_inited_xattr(inode);
>>> + return 0;
>>> }
>>>
>>> struct xattr_iter_handlers {
>>> @@ -101,19 +116,24 @@ struct xattr_iter_handlers {
>>> void (*value)(struct xattr_iter *, unsigned, char *, unsigned);
>>> };
>>>
>>> -static void xattr_iter_fixup(struct xattr_iter *it)
>>> +static inline int xattr_iter_fixup(struct xattr_iter *it)
>>> {
>>> - if (unlikely(it->ofs >= EROFS_BLKSIZ)) {
>>> - xattr_iter_end(it, true);
>>> + if (likely(it->ofs < EROFS_BLKSIZ))
>>> + return 0;
>>>
>>> - it->blkaddr += erofs_blknr(it->ofs);
>>> - it->page = erofs_get_meta_page_nofail(it->sb,
>>> - it->blkaddr, false);
>>> - BUG_ON(IS_ERR(it->page));
>>> + xattr_iter_end(it, true);
>>>
>>> - it->kaddr = kmap_atomic(it->page);
>>> - it->ofs = erofs_blkoff(it->ofs);
>>> + it->blkaddr += erofs_blknr(it->ofs);
>>> +
>>> + it->page = erofs_get_meta_page(it->sb, it->blkaddr, false);
>>> + if (unlikely(IS_ERR(it->page))) {
>>> + it->page = NULL;
>>> + return PTR_ERR(it->page);
>>> }
>>> +
>>> + it->kaddr = kmap_atomic(it->page);
>>> + it->ofs = erofs_blkoff(it->ofs);
>>> + return 0;
>>> }
>>>
>>> static int inline_xattr_iter_begin(struct xattr_iter *it,
>>> @@ -135,21 +155,24 @@ static int inline_xattr_iter_begin(struct xattr_iter *it,
>>> it->ofs = erofs_blkoff(iloc(sbi, vi->nid) + inline_xattr_ofs);
>>>
>>> it->page = erofs_get_inline_page_nofail(inode, it->blkaddr);
>>
>> Ditto,
>>
> This should be converted into erofs_get_inline_page actually... I'm lazy about that, sorry...
> Let me send another patch..
>
> Thanks,
> Gao Xiang
>
>>> - BUG_ON(IS_ERR(it->page));
>>> - it->kaddr = kmap_atomic(it->page);
>>> + if (unlikely(IS_ERR(it->page)))
>>> + return PTR_ERR(it->page);
>>>
>>> + it->kaddr = kmap_atomic(it->page);
>>> return vi->xattr_isize - xattr_header_sz;
>>> }
>>>
>>> static int xattr_foreach(struct xattr_iter *it,
>>> - struct xattr_iter_handlers *op, unsigned *tlimit)
>>> + const struct xattr_iter_handlers *op, unsigned *tlimit)
>>> {
>>> struct erofs_xattr_entry entry;
>>> unsigned value_sz, processed, slice;
>>> int err;
>>>
>>> /* 0. fixup blkaddr, ofs, ipage */
>>> - xattr_iter_fixup(it);
>>> + err = xattr_iter_fixup(it);
>>> + if (unlikely(err))
>>> + return err;
>>>
>>> /*
>>> * 1. read xattr entry to the memory,
>>> @@ -181,7 +204,9 @@ static int xattr_foreach(struct xattr_iter *it,
>>> if (it->ofs >= EROFS_BLKSIZ) {
>>> BUG_ON(it->ofs > EROFS_BLKSIZ);
>>>
>>> - xattr_iter_fixup(it);
>>> + err = xattr_iter_fixup(it);
>>> + if (unlikely(err))
>>> + goto out;
>>> it->ofs = 0;
>>> }
>>>
>>> @@ -213,7 +238,10 @@ static int xattr_foreach(struct xattr_iter *it,
>>> while (processed < value_sz) {
>>> if (it->ofs >= EROFS_BLKSIZ) {
>>> BUG_ON(it->ofs > EROFS_BLKSIZ);
>>> - xattr_iter_fixup(it);
>>> +
>>> + err = xattr_iter_fixup(it);
>>> + if (unlikely(err))
>>> + goto out;
>>> it->ofs = 0;
>>> }
>>>
>>> @@ -273,7 +301,7 @@ static void xattr_copyvalue(struct xattr_iter *_it,
>>> memcpy(it->buffer + processed, buf, len);
>>> }
>>>
>>> -static struct xattr_iter_handlers find_xattr_handlers = {
>>> +static const struct xattr_iter_handlers find_xattr_handlers = {
>>> .entry = xattr_entrymatch,
>>> .name = xattr_namematch,
>>> .alloc_buffer = xattr_checkbuffer,
>>> @@ -294,8 +322,11 @@ static int inline_getxattr(struct inode *inode, struct getxattr_iter *it)
>>> if ((ret = xattr_foreach(&it->it,
>>> &find_xattr_handlers, &remaining)) >= 0)
>>> break;
>>> +
>>> + if (unlikely(ret != -ENOATTR)) /* -ENOMEM, -EIO, etc. */
>>> + break;
>>> }
>>> - xattr_iter_end(&it->it, true);
>>> + xattr_iter_end_final(&it->it);
>>>
>>> return ret < 0 ? ret : it->buffer_size;
>>> }
>>> @@ -318,9 +349,10 @@ static int shared_getxattr(struct inode *inode, struct getxattr_iter *it)
>>> if (i)
>>> xattr_iter_end(&it->it, true);
>>>
>>> - it->it.page = erofs_get_meta_page_nofail(sb,
>>> - blkaddr, false);
>>> - BUG_ON(IS_ERR(it->it.page));
>>> + it->it.page = erofs_get_meta_page(sb, blkaddr, false);
>>> + if (unlikely(IS_ERR(it->it.page)))
>>> + return PTR_ERR(it->it.page);
>>> +
>>> it->it.kaddr = kmap_atomic(it->it.page);
>>> it->it.blkaddr = blkaddr;
>>> }
>>> @@ -328,9 +360,12 @@ static int shared_getxattr(struct inode *inode, struct getxattr_iter *it)
>>> if ((ret = xattr_foreach(&it->it,
>>> &find_xattr_handlers, NULL)) >= 0)
>>> break;
>>> +
>>> + if (unlikely(ret != -ENOATTR)) /* -ENOMEM, -EIO, etc. */
>>> + break;
>>> }
>>> if (vi->xattr_shared_count)
>>> - xattr_iter_end(&it->it, true);
>>> + xattr_iter_end_final(&it->it);
>>>
>>> return ret < 0 ? ret : it->buffer_size;
>>> }
>>> @@ -355,7 +390,9 @@ int erofs_getxattr(struct inode *inode, int index,
>>> if (unlikely(name == NULL))
>>> return -EINVAL;
>>>
>>> - init_inode_xattrs(inode);
>>> + ret = init_inode_xattrs(inode);
>>> + if (unlikely(ret < 0))
>>> + return ret;
>>>
>>> it.index = index;
>>>
>>> @@ -498,7 +535,7 @@ static int xattr_skipvalue(struct xattr_iter *_it,
>>> return 1;
>>> }
>>>
>>> -static struct xattr_iter_handlers list_xattr_handlers = {
>>> +static const struct xattr_iter_handlers list_xattr_handlers = {
>>> .entry = xattr_entrylist,
>>> .name = xattr_namelist,
>>> .alloc_buffer = xattr_skipvalue,
>>> @@ -520,7 +557,7 @@ static int inline_listxattr(struct listxattr_iter *it)
>>> &list_xattr_handlers, &remaining)) < 0)
>>> break;
>>> }
>>> - xattr_iter_end(&it->it, true);
>>> + xattr_iter_end_final(&it->it);
>>> return ret < 0 ? ret : it->buffer_ofs;
>>> }
>>>
>>> @@ -542,9 +579,10 @@ static int shared_listxattr(struct listxattr_iter *it)
>>> if (i)
>>> xattr_iter_end(&it->it, true);
>>>
>>> - it->it.page = erofs_get_meta_page_nofail(sb,
>>> - blkaddr, false);
>>> - BUG_ON(IS_ERR(it->it.page));
>>> + it->it.page = erofs_get_meta_page(sb, blkaddr, false);
>>> + if (unlikely(IS_ERR(it->it.page)))
>>> + return PTR_ERR(it->it.page);
>>> +
>>> it->it.kaddr = kmap_atomic(it->it.page);
>>> it->it.blkaddr = blkaddr;
>>> }
>>> @@ -554,7 +592,7 @@ static int shared_listxattr(struct listxattr_iter *it)
>>> break;
>>> }
>>> if (vi->xattr_shared_count)
>>> - xattr_iter_end(&it->it, true);
>>> + xattr_iter_end_final(&it->it);
>>>
>>> return ret < 0 ? ret : it->buffer_ofs;
>>> }
>>> @@ -565,7 +603,9 @@ ssize_t erofs_listxattr(struct dentry *dentry,
>>> int ret;
>>> struct listxattr_iter it;
>>>
>>> - init_inode_xattrs(d_inode(dentry));
>>> + ret = init_inode_xattrs(d_inode(dentry));
>>> + if (unlikely(ret < 0))
>>> + return ret;
>>>
>>> it.dentry = dentry;
>>> it.buffer = buffer;
>>>
>>
>
> .
>
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