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Message-Id: <1375681420-15384-3-git-send-email-wenqing.lz@taobao.com>
Date: Mon, 5 Aug 2013 13:43:40 +0800
From: Zheng Liu <gnehzuil.liu@...il.com>
To: linux-ext4@...r.kernel.org
Cc: Zheng Liu <wenqing.lz@...bao.com>, "Theodore Ts'o" <tytso@....edu>
Subject: [PATCH v5 2/2] debugfs: dump a sparse file
From: Zheng Liu <wenqing.lz@...bao.com>
When ext2fs_file_open() is called with EXT2_FILE_SPAESE flag, ext2fs_file_read()
will return EXT2_ET_READ_HOLE_FOUND if it meets a hole/uninitialized block.
Signed-off-by: Zheng Liu <wenqing.lz@...bao.com>
Cc: "Theodore Ts'o" <tytso@....edu>
---
debugfs/dump.c | 48 +++++++++++++++++++++++++++++++++++++--------
lib/ext2fs/ext2_err.et.in | 3 +++
lib/ext2fs/ext2fs.h | 1 +
lib/ext2fs/fileio.c | 11 +++++++++--
4 files changed, 53 insertions(+), 10 deletions(-)
diff --git a/debugfs/dump.c b/debugfs/dump.c
index c75b9f1..5431a7b 100644
--- a/debugfs/dump.c
+++ b/debugfs/dump.c
@@ -107,13 +107,20 @@ static void dump_file(const char *cmdname, ext2_ino_t ino, int fd,
struct ext2_inode inode;
char *buf = 0;
ext2_file_t e2_file;
- int nbytes;
+ ext2_off64_t ret_pos, offset;
+ int nbytes, flags = 0;
unsigned int got, blocksize = current_fs->blocksize;
if (debugfs_read_inode(ino, &inode, cmdname))
return;
- retval = ext2fs_file_open(current_fs, ino, 0, &e2_file);
+ /*
+ * We need to handle stdout because this function is called by
+ * do_cat() and do_dump().
+ */
+ if (fd != 1)
+ flags = EXT2_FILE_SPARSE;
+ retval = ext2fs_file_open(current_fs, ino, flags, &e2_file);
if (retval) {
com_err(cmdname, retval, "while opening ext2 file");
return;
@@ -125,13 +132,38 @@ static void dump_file(const char *cmdname, ext2_ino_t ino, int fd,
}
while (1) {
retval = ext2fs_file_read(e2_file, buf, blocksize, &got);
- if (retval)
+ if (retval && retval != EXT2_ET_READ_HOLE_FOUND)
com_err(cmdname, retval, "while reading ext2 file");
- if (got == 0)
- break;
- nbytes = write(fd, buf, got);
- if ((unsigned) nbytes != got)
- com_err(cmdname, errno, "while writing file");
+ if (retval == EXT2_ET_READ_HOLE_FOUND) {
+ if (got) {
+ nbytes = write(fd, buf, got);
+ if ((unsigned) nbytes != got)
+ com_err(cmdname, errno,
+ "while writing file");
+ }
+ retval = ext2fs_file_llseek(e2_file, 0, EXT2_SEEK_CUR,
+ &offset);
+ if (retval)
+ com_err(cmdname, retval,
+ "while lseeking ext2 file");
+ retval = ext2fs_file_llseek(e2_file, offset,
+ EXT2_SEEK_DATA, &ret_pos);
+ if (retval == EXT2_ET_SEEK_BEYOND_EOF)
+ break;
+ if (retval)
+ com_err(cmdname, retval,
+ "while lseeking ext2 file");
+ ret_pos = ext2fs_llseek(fd, ret_pos, SEEK_SET);
+ if (ret_pos < 0)
+ com_err(cmdname, retval,
+ "while lseeking target file");
+ } else {
+ if (got == 0)
+ break;
+ nbytes = write(fd, buf, got);
+ if ((unsigned) nbytes != got)
+ com_err(cmdname, errno, "while writing file");
+ }
}
if (buf)
ext2fs_free_mem(&buf);
diff --git a/lib/ext2fs/ext2_err.et.in b/lib/ext2fs/ext2_err.et.in
index 6e79b97..f854df0 100644
--- a/lib/ext2fs/ext2_err.et.in
+++ b/lib/ext2fs/ext2_err.et.in
@@ -479,4 +479,7 @@ ec EXT2_ET_FILE_EXISTS,
ec EXT2_ET_SEEK_BEYOND_EOF,
"lseek beyond the EOF"
+ec EXT2_ET_READ_HOLE_FOUND,
+ "We read a hole/uninitialized block with EXT2_FILE_SPARSE flag"
+
end
diff --git a/lib/ext2fs/ext2fs.h b/lib/ext2fs/ext2fs.h
index 2a9ddbb..279087b 100644
--- a/lib/ext2fs/ext2fs.h
+++ b/lib/ext2fs/ext2fs.h
@@ -149,6 +149,7 @@ typedef struct ext2_struct_dblist *ext2_dblist;
#define EXT2_FILE_WRITE 0x0001
#define EXT2_FILE_CREATE 0x0002
+#define EXT2_FILE_SPARSE 0x0004
#define EXT2_FILE_MASK 0x00FF
diff --git a/lib/ext2fs/fileio.c b/lib/ext2fs/fileio.c
index 6cb2e43..be658d8 100644
--- a/lib/ext2fs/fileio.c
+++ b/lib/ext2fs/fileio.c
@@ -185,11 +185,12 @@ static errcode_t load_buffer(ext2_file_t file, int dontfill)
{
ext2_filsys fs = file->fs;
errcode_t retval;
+ int ret_flags = 0;
if (!(file->flags & EXT2_FILE_BUF_VALID)) {
retval = ext2fs_bmap2(fs, file->ino, &file->inode,
- BMAP_BUFFER, 0, file->blockno, 0,
- &file->physblock);
+ BMAP_BUFFER, 0, file->blockno,
+ &ret_flags, &file->physblock);
if (retval)
return retval;
if (!dontfill) {
@@ -203,6 +204,12 @@ static errcode_t load_buffer(ext2_file_t file, int dontfill)
memset(file->buf, 0, fs->blocksize);
}
file->flags |= EXT2_FILE_BUF_VALID;
+ if (file->flags & EXT2_FILE_SPARSE) {
+ if (file->physblock == 0 ||
+ (ret_flags & BMAP_RET_UNINIT)) {
+ return EXT2_ET_READ_HOLE_FOUND;
+ }
+ }
}
return 0;
}
--
1.7.9.7
--
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