[PATCH 4/5] erofs-utils: handle mmap failure when packing a whole file

[Gao Xiang]

Directly read/write if mmap failure.

Signed-off-by: Gao Xiang <hsiang...@linux.alibaba.com>
---
 lib/fragments.c | 43 +++++++++++++++++++++++++++++++++++--------
 1 file changed, 35 insertions(+), 8 deletions(-)

diff --git a/lib/fragments.c b/lib/fragments.c
index ebff4b5..30e9ba6 100644
--- a/lib/fragments.c
+++ b/lib/fragments.c
@@ -223,14 +223,39 @@ int z_erofs_pack_file_from_fd(struct erofs_inode *inode, 
int fd,
        if (offset < 0)
                return -errno;
 
-       memblock = mmap(NULL, inode->i_size, PROT_READ, MAP_SHARED, fd, 0);
-       if (memblock == MAP_FAILED)
-               return -EFAULT;
-
        inode->fragmentoff = (erofs_off_t)offset;
        inode->fragment_size = inode->i_size;
 
-       if (fwrite(memblock, inode->fragment_size, 1, packedfile) != 1) {
+       memblock = mmap(NULL, inode->i_size, PROT_READ, MAP_SHARED, fd, 0);
+       if (memblock == MAP_FAILED || !memblock) {
+               unsigned long long remaining = inode->fragment_size;
+
+               memblock = NULL;
+               while (remaining) {
+                       char buf[32768];
+                       unsigned int sz = min_t(unsigned int, remaining,
+                                               sizeof(buf));
+
+                       rc = read(fd, buf, sz);
+                       if (rc != sz) {
+                               if (rc < 0)
+                                       rc = -errno;
+                               else
+                                       rc = -EAGAIN;
+                               goto out;
+                       }
+                       if (fwrite(buf, sz, 1, packedfile) != 1) {
+                               rc = -EIO;
+                               goto out;
+                       }
+                       remaining -= sz;
+               }
+               rc = lseek(fd, 0, SEEK_SET);
+               if (rc < 0) {
+                       rc = -errno;
+                       goto out;
+               }
+       } else if (fwrite(memblock, inode->fragment_size, 1, packedfile) != 1) {
                rc = -EIO;
                goto out;
        }
@@ -238,10 +263,12 @@ int z_erofs_pack_file_from_fd(struct erofs_inode *inode, 
int fd,
        erofs_dbg("Recording %u fragment data at %lu", inode->fragment_size,
                  inode->fragmentoff);
 
-       rc = z_erofs_fragments_dedupe_insert(memblock, inode->fragment_size,
-                                            inode->fragmentoff, tofcrc);
+       if (memblock)
+               rc = z_erofs_fragments_dedupe_insert(memblock,
+                       inode->fragment_size, inode->fragmentoff, tofcrc);
 out:
-       munmap(memblock, inode->i_size);
+       if (memblock)
+               munmap(memblock, inode->i_size);
        return rc;
 }
 
-- 
2.24.4