ext4: clean up ext4_xattr_inode_get()

The input and output values of *size parameter are equal on successful
return from ext4_xattr_inode_get().  On error return, the callers ignore
the output value so there is no need to update it.

Also check for NULL return from ext4_bread().  If the actual xattr inode
size happens to be smaller than the expected size, ext4_bread() may
return NULL which would indicate data corruption.

Signed-off-by: Tahsin Erdogan <tahsin@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c
index f16a908..61c67a0 100644 (file)
--- a/fs/ext4/xattr.c
+++ b/fs/ext4/xattr.c
@@ -278,37 +278,28 @@ ext4_xattr_find_entry(struct ext4_xattr_entry **pentry, int name_index,
 /*
  * Read the EA value from an inode.
  */
-static int
-ext4_xattr_inode_read(struct inode *ea_inode, void *buf, size_t *size)
+static int ext4_xattr_inode_read(struct inode *ea_inode, void *buf, size_t size)
 {
        unsigned long block = 0;
        struct buffer_head *bh = NULL;
-       int blocksize;
-       size_t csize, ret_size = 0;
-
-       if (*size == 0)
-               return 0;
+       int blocksize = ea_inode->i_sb->s_blocksize;
+       size_t csize, copied = 0;
 
-       blocksize = ea_inode->i_sb->s_blocksize;
-
-       while (ret_size < *size) {
-               csize = (*size - ret_size) > blocksize ? blocksize :
-                                                       *size - ret_size;
+       while (copied < size) {
+               csize = (size - copied) > blocksize ? blocksize : size - copied;
                bh = ext4_bread(NULL, ea_inode, block, 0);
-               if (IS_ERR(bh)) {
-                       *size = ret_size;
+               if (IS_ERR(bh))
                        return PTR_ERR(bh);
-               }
+               if (!bh)
+                       return -EFSCORRUPTED;
+
                memcpy(buf, bh->b_data, csize);
                brelse(bh);
 
                buf += csize;
                block += 1;
-               ret_size += csize;
+               copied += csize;
        }
-
-       *size = ret_size;
-
        return 0;
 }
 
@@ -360,7 +351,7 @@ error:
  */
 static int
 ext4_xattr_inode_get(struct inode *inode, unsigned long ea_ino, void *buffer,
-                    size_t *size)
+                    size_t size)
 {
        struct inode *ea_inode;
        int ret;
@@ -417,7 +408,7 @@ ext4_xattr_block_get(struct inode *inode, int name_index, const char *name,
                if (entry->e_value_inum) {
                        error = ext4_xattr_inode_get(inode,
                                             le32_to_cpu(entry->e_value_inum),
-                                            buffer, &size);
+                                            buffer, size);
                        if (error)
                                goto cleanup;
                } else {
@@ -467,7 +458,7 @@ ext4_xattr_ibody_get(struct inode *inode, int name_index, const char *name,
                if (entry->e_value_inum) {
                        error = ext4_xattr_inode_get(inode,
                                             le32_to_cpu(entry->e_value_inum),
-                                            buffer, &size);
+                                            buffer, size);
                        if (error)
                                goto cleanup;
                } else {