[PATCH v2 3/8] staging: erofs: add error handling for xattr submodule

Gao Xiang
2018-08-13T02:57:16Z

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@huawei.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Chao Yu <yuchao0@huawei.com>
---
change log v2:
- fix `PTR_ERR applied after initialization to constant' reported by
kbuild test robot <lkp@intel.com>
Link: https://lists.01.org/pipermail/kbuild-all/2018-August/051187.html

drivers/staging/erofs/internal.h | 6 +-
drivers/staging/erofs/xattr.c | 122 ++++++++++++++++++++++++++-------------
2 files changed, 85 insertions(+), 43 deletions(-)

diff --git a/drivers/staging/erofs/internal.h b/drivers/staging/erofs/internal.h
index a756abe..8951e01 100644
--- a/drivers/staging/erofs/internal.h
+++ b/drivers/staging/erofs/internal.h
@@ -485,10 +485,10 @@ struct erofs_map_blocks_iter {

static inline struct page *
-erofs_get_inline_page_nofail(struct inode *inode,
- erofs_blk_t blkaddr)
+erofs_get_inline_page(struct inode *inode,
+ erofs_blk_t blkaddr)
{
- return erofs_get_meta_page_nofail(inode->i_sb,
+ return erofs_get_meta_page(inode->i_sb,
blkaddr, S_ISDIR(inode->i_mode));
}

diff --git a/drivers/staging/erofs/xattr.c b/drivers/staging/erofs/xattr.c
index 2593c85..2a846cf 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);
@@ -54,8 +63,9 @@ static void init_inode_xattrs(struct inode *inode)
it.blkaddr = erofs_blknr(iloc(sbi, vi->nid) + vi->inode_isize);
it.ofs = erofs_blkoff(iloc(sbi, vi->nid) + vi->inode_isize);

- it.page = erofs_get_inline_page_nofail(inode, it.blkaddr);
- BUG_ON(IS_ERR(it.page));
+ it.page = erofs_get_inline_page(inode, it.blkaddr);
+ if (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);
@@ -77,9 +90,10 @@ static void init_inode_xattrs(struct inode *inode)
BUG_ON(it.ofs != EROFS_BLKSIZ);
xattr_iter_end(&it, atomic_map);

- it.page = erofs_get_meta_page_nofail(sb,
+ it.page = erofs_get_meta_page(sb,
++it.blkaddr, S_ISDIR(inode->i_mode));
- BUG_ON(IS_ERR(it.page));
+ if (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 +116,26 @@ 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;
+
+ xattr_iter_end(it, true);

- it->blkaddr += erofs_blknr(it->ofs);
- it->page = erofs_get_meta_page_nofail(it->sb,
- it->blkaddr, false);
- BUG_ON(IS_ERR(it->page));
+ it->blkaddr += erofs_blknr(it->ofs);

- it->kaddr = kmap_atomic(it->page);
- it->ofs = erofs_blkoff(it->ofs);
+ it->page = erofs_get_meta_page(it->sb, it->blkaddr, false);
+ if (IS_ERR(it->page)) {
+ int err = PTR_ERR(it->page);
+
+ it->page = NULL;
+ return err;
}
+
+ it->kaddr = kmap_atomic(it->page);
+ it->ofs = erofs_blkoff(it->ofs);
+ return 0;
}

static int inline_xattr_iter_begin(struct xattr_iter *it,
@@ -134,22 +156,25 @@ static int inline_xattr_iter_begin(struct xattr_iter *it,
it->blkaddr = erofs_blknr(iloc(sbi, vi->nid) + inline_xattr_ofs);
it->ofs = erofs_blkoff(iloc(sbi, vi->nid) + inline_xattr_ofs);

- it->page = erofs_get_inline_page_nofail(inode, it->blkaddr);
- BUG_ON(IS_ERR(it->page));
- it->kaddr = kmap_atomic(it->page);
+ it->page = erofs_get_inline_page(inode, it->blkaddr);
+ if (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 +206,9 @@ 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 +240,10 @@ 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 +303,7 @@ 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 +324,11 @@ static int inline_getxattr(struct inode *inode, struct getxattr_iter *it)
ret = xattr_foreach(&it->it, &find_xattr_handlers, &remaining);
if (ret >= 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 +351,10 @@ 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 (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 +362,12 @@ static int shared_getxattr(struct inode *inode, struct getxattr_iter *it)
ret = xattr_foreach(&it->it, &find_xattr_handlers, NULL);
if (ret >= 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 +392,9 @@ 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 +537,7 @@ 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 +559,7 @@ static int inline_listxattr(struct listxattr_iter *it)
if (ret < 0)
break;
}
- xattr_iter_end(&it->it, true);
+ xattr_iter_end_final(&it->it);
return ret < 0 ? ret : it->buffer_ofs;
}

@@ -542,9 +581,10 @@ 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 (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 +594,7 @@ 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 +605,9 @@ 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;
--
1.9.1