qnx4_block_map() may return -EIO on funny qnx4 fs image, in this case do
not interpret error as a valid block number.

Signed-off-by: Tong Zhang <ztong0...@gmail.com>
---
v2: also check other callers according to Anders Larsen's<a...@alarsen.net> 
comment
v3: change error code from EIO to ~0ull to avoid potential compiler
warning on signed/unsigned comparison
v4: revert error code back to -EIO and dedicate return value for error code. 
Also
print a message to let user know there is an error.
 fs/qnx4/dir.c   |  5 ++++-
 fs/qnx4/inode.c | 14 +++++++++-----
 fs/qnx4/namei.c |  6 +++++-
 fs/qnx4/qnx4.h  |  2 +-
 4 files changed, 19 insertions(+), 8 deletions(-)

diff --git a/fs/qnx4/dir.c b/fs/qnx4/dir.c
index a6ee23aadd28..49ccd7ddd83b 100644
--- a/fs/qnx4/dir.c
+++ b/fs/qnx4/dir.c
@@ -25,12 +25,15 @@ static int qnx4_readdir(struct file *file, struct 
dir_context *ctx)
        unsigned long blknum;
        int ix, ino;
        int size;
+       int result;
 
        QNX4DEBUG((KERN_INFO "qnx4_readdir:i_size = %ld\n", (long) 
inode->i_size));
        QNX4DEBUG((KERN_INFO "pos                 = %ld\n", (long) ctx->pos));
 
        while (ctx->pos < inode->i_size) {
-               blknum = qnx4_block_map(inode, ctx->pos >> 
QNX4_BLOCK_SIZE_BITS);
+               result = qnx4_block_map(inode, ctx->pos >> 
QNX4_BLOCK_SIZE_BITS, &blknum);
+               if (result)
+                       return result;
                bh = sb_bread(inode->i_sb, blknum);
                if (bh == NULL) {
                        printk(KERN_ERR "qnx4_readdir: bread failed (%ld)\n", 
blknum);
diff --git a/fs/qnx4/inode.c b/fs/qnx4/inode.c
index e8da1cde87b9..3333a4ef65fe 100644
--- a/fs/qnx4/inode.c
+++ b/fs/qnx4/inode.c
@@ -54,11 +54,14 @@ static int qnx4_remount(struct super_block *sb, int *flags, 
char *data)
 
 static int qnx4_get_block( struct inode *inode, sector_t iblock, struct 
buffer_head *bh, int create )
 {
+       int result;
        unsigned long phys;
 
        QNX4DEBUG((KERN_INFO "qnx4: qnx4_get_block inode=[%ld] 
iblock=[%ld]\n",inode->i_ino,iblock));
 
-       phys = qnx4_block_map( inode, iblock );
+       result = qnx4_block_map(inode, iblock, &phys);
+       if (result)
+               return result;
        if ( phys ) {
                // logical block is before EOF
                map_bh(bh, inode->i_sb, phys);
@@ -75,7 +78,7 @@ static inline u32 try_extent(qnx4_xtnt_t *extent, u32 *offset)
        return 0;
 }
 
-unsigned long qnx4_block_map( struct inode *inode, long iblock )
+int qnx4_block_map(struct inode *inode, long iblock , unsigned long *phys)
 {
        int ix;
        long i_xblk;
@@ -97,12 +100,12 @@ unsigned long qnx4_block_map( struct inode *inode, long 
iblock )
                                // read next xtnt block.
                                bh = sb_bread(inode->i_sb, i_xblk - 1);
                                if ( !bh ) {
-                                       QNX4DEBUG((KERN_ERR "qnx4: I/O error 
reading xtnt block [%ld])\n", i_xblk - 1));
+                                       printk(KERN_ERR "qnx4: I/O error 
reading xtnt block [%ld])\n", i_xblk - 1);
                                        return -EIO;
                                }
                                xblk = (struct qnx4_xblk*)bh->b_data;
                                if ( memcmp( xblk->xblk_signature, "IamXblk", 7 
) ) {
-                                       QNX4DEBUG((KERN_ERR "qnx4: block at %ld 
is not a valid xtnt\n", qnx4_inode->i_xblk));
+                                       printk(KERN_ERR "qnx4: block at %d is 
not a valid xtnt\n", qnx4_inode->di_xblk);
                                        return -EIO;
                                }
                        }
@@ -123,7 +126,8 @@ unsigned long qnx4_block_map( struct inode *inode, long 
iblock )
        }
 
        QNX4DEBUG((KERN_INFO "qnx4: mapping block %ld of inode %ld = 
%ld\n",iblock,inode->i_ino,block));
-       return block;
+       *phys = block;
+       return 0;
 }
 
 static int qnx4_statfs(struct dentry *dentry, struct kstatfs *buf)
diff --git a/fs/qnx4/namei.c b/fs/qnx4/namei.c
index 8d72221735d7..3d64b34dbe6e 100644
--- a/fs/qnx4/namei.c
+++ b/fs/qnx4/namei.c
@@ -59,13 +59,16 @@ static struct buffer_head *qnx4_find_entry(int len, struct 
inode *dir,
 {
        unsigned long block, offset, blkofs;
        struct buffer_head *bh;
+       int result;
 
        *res_dir = NULL;
        bh = NULL;
        block = offset = blkofs = 0;
        while (blkofs * QNX4_BLOCK_SIZE + offset < dir->i_size) {
                if (!bh) {
-                       block = qnx4_block_map(dir, blkofs);
+                       result = qnx4_block_map(dir, blkofs, &block);
+                       if (result)
+                               goto out;
                        if (block)
                                bh = sb_bread(dir->i_sb, block);
                        if (!bh) {
@@ -88,6 +91,7 @@ static struct buffer_head *qnx4_find_entry(int len, struct 
inode *dir,
                blkofs++;
        }
        brelse(bh);
+out:
        *res_dir = NULL;
        return NULL;
 }
diff --git a/fs/qnx4/qnx4.h b/fs/qnx4/qnx4.h
index 6283705466a4..efa76aa551fc 100644
--- a/fs/qnx4/qnx4.h
+++ b/fs/qnx4/qnx4.h
@@ -24,7 +24,7 @@ struct qnx4_inode_info {
 extern struct inode *qnx4_iget(struct super_block *, unsigned long);
 extern struct dentry *qnx4_lookup(struct inode *dir, struct dentry *dentry, 
unsigned int flags);
 extern unsigned long qnx4_count_free_blocks(struct super_block *sb);
-extern unsigned long qnx4_block_map(struct inode *inode, long iblock);
+extern int qnx4_block_map(struct inode *inode, long iblock, unsigned long* 
phys);
 
 extern const struct inode_operations qnx4_dir_inode_operations;
 extern const struct file_operations qnx4_dir_operations;
-- 
2.25.1

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