From 83e965dc6ec45e5c9811a27023c9cc213d50816b Mon Sep 17 00:00:00 2001
From: Chen Linxuan <[email protected]>
Date: Thu, 20 Oct 2022 17:53:03 +0800
Subject: [PATCH] erofs-utils: erofs-utils: lib: fix dev_read
When using `fsck.erofs` to extract some image have a very large file
inside, for example 2G, my fsck.erofs report some thing like this:
<E> erofs_io: Failed to read data from device - erofs.image:[4096,
2147483648].
<E> erofs: failed to read data of m_pa 4096, m_plen 2147483648 @ nid 40: -17
<E> erofs: Failed to extract filesystem
You can use this script to reproduce this issue.
mkdir tmp extract
dd if=/dev/urandom of=tmp/big_file bs=1M count=2048
mkfs.erofs erofs.image tmp
fsck.erofs erofs.image --extract=extract
I found that dev_open will failed if we can not get all data we want
with one pread call.
I write this little patch try to fix this issue.
Signed-off-by: Chen Linxuan <[email protected]>
---
lib/io.c | 28 +++++++++++++++++++++-------
1 file changed, 21 insertions(+), 7 deletions(-)
diff --git a/lib/io.c b/lib/io.c
index 524cfb4..5cb2b3a 100644
--- a/lib/io.c
+++ b/lib/io.c
@@ -256,7 +256,7 @@ int dev_resize(unsigned int blocks)
int dev_read(int device_id, void *buf, u64 offset, size_t len)
{
- int ret, fd;
+ int read_count, fd;
if (cfg.c_dry_run)
return 0;
@@ -278,15 +278,29 @@ int dev_read(int device_id, void *buf, u64 offset,
size_t len)
fd = erofs_blobfd[device_id - 1];
}
+ while (len > 0) {
#ifdef HAVE_PREAD64
- ret = pread64(fd, buf, len, (off64_t)offset);
+ read_count = pread64(fd, buf, len, (off64_t)offset);
#else
- ret = pread(fd, buf, len, (off_t)offset);
+ read_count = pread(fd, buf, len, (off_t)offset);
#endif
- if (ret != (int)len) {
- erofs_err("Failed to read data from device - %s:[%" PRIu64 ",
%zd].",
- erofs_devname, offset, len);
- return -errno;
+ if (read_count == -1 || read_count == 0) {
+ if (errno) {
+ erofs_err("Failed to read data from device - "
+ "%s:[%" PRIu64 ", %zd].",
+ erofs_devname, offset, len);
+ return -errno;
+ } else {
+ erofs_err("Reach EOF of device - "
+ "%s:[%" PRIu64 ", %zd].",
+ erofs_devname, offset, len);
+ return -EINVAL;
+ }
+ }
+
+ offset += read_count;
+ len -= read_count;
+ buf += read_count;
}
return 0;
}
--
2.37.3
On 2022/10/20 17:24, Gao Xiang wrote:
Hi LinXuan,
On Thu, Oct 20, 2022 at 04:12:57PM +0800, chenlinxuan wrote:
When using `fsck.erofs` to extract some image have a very large file (3G)
inside, my fsck.erofs report some thing like:
<E> erofs_io: Failed to read data from device - erofs.image:[4096,
2147483648].
<E> erofs: failed to read data of m_pa 4096, m_plen 2147483648 @ nid 40: -17
<E> erofs: Failed to extract filesystem
You can use this script to reproduce this issue.
#!/bin/env sh
mkdir tmp extract
dd if=/dev/urandom of=tmp/big_file bs=1M count=2048
mkfs.erofs erofs.image tmp
fsck.erofs erofs.image --extract=extract
I found that dev_open will failed if we can not get all data we want with
one pread call.
I write this little patch try to fix this issue.
This is my first patch send via email, sorry if anything goes wrong.
Thanks for your report, and the issue looks true.
In order to merge this patch, could you apply the message above into
the commit message?
BTW, the commit message can be updated with "git commit --amend".
From 156af5b173c1f9e2a91e4d2126214b96966babd1 Mon Sep 17 00:00:00 2001
From: chenlinxuan <[email protected]>
It would be better to update your real name into
"Linxuan Chen" Or "Chen Linxuan" (whichever you prefer).
Date: Thu, 20 Oct 2022 14:39:17 +0800
Subject: [PATCH] erofs-utils: lib: fix dev_read
Subject title:
"erofs-utils: lib: fix dev_read to make it works with large file"
We need to keep calling pread until we get all data we want
---
lib/io.c | 28 +++++++++++++++++++++-------
1 file changed, 21 insertions(+), 7 deletions(-)
diff --git a/lib/io.c b/lib/io.c
index 524cfb4..bd3d790 100644
--- a/lib/io.c
+++ b/lib/io.c
@@ -256,7 +256,7 @@ int dev_resize(unsigned int blocks)
int dev_read(int device_id, void *buf, u64 offset, size_t len)
{
- int ret, fd;
+ int read_count, fd;
if (cfg.c_dry_run)
return 0;
@@ -278,15 +278,29 @@ int dev_read(int device_id, void *buf, u64 offset,
size_t len)
fd = erofs_blobfd[device_id - 1];
}
+ while (len > 0) {
#ifdef HAVE_PREAD64
- ret = pread64(fd, buf, len, (off64_t)offset);
+ read_count = pread64(fd, buf, len, (off64_t)offset);
#else
- ret = pread(fd, buf, len, (off_t)offset);
+ read_count = pread(fd, buf, len, (off_t)offset);
#endif
- if (ret != (int)len) {
- erofs_err("Failed to read data from device - %s:[%" PRIu64 ",
%zd].",
- erofs_devname, offset, len);
- return -errno;
+ if (read_count == -1 || read_count == 0) {
^ extra space here.
Thanks,
Gao Xiang
