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Date: Tue, 10 Dec 2013 17:23:53 -0800
From: "Darrick J. Wong" <darrick.wong@...cle.com>
To: tytso@....edu, darrick.wong@...cle.com
Cc: linux-ext4@...r.kernel.org
Subject: [PATCH 50/74] libext2fs: support allocating uninit blocks in bmap2()
In order to support fallocate, we need to be able to have
ext2fs_bmap2() allocate blocks and put them into uninitialized
extents. There's a flag to do this in the extent code, but it's not
exposed to the bmap2 interface, so plumb that in. Eventually fuse2fs
or somebody will use it.
Signed-off-by: Darrick J. Wong <darrick.wong@...cle.com>
---
lib/ext2fs/bmap.c | 49 +++++++++++++++++++++++++++++++++++++++++++++++--
lib/ext2fs/ext2fs.h | 1 +
2 files changed, 48 insertions(+), 2 deletions(-)
diff --git a/lib/ext2fs/bmap.c b/lib/ext2fs/bmap.c
index 3a18d76..ca89eb1 100644
--- a/lib/ext2fs/bmap.c
+++ b/lib/ext2fs/bmap.c
@@ -33,6 +33,32 @@ extern errcode_t ext2fs_bmap(ext2_filsys fs, ext2_ino_t ino,
#define inode_bmap(inode, nr) ((inode)->i_block[(nr)])
+static errcode_t zero_block(ext2_filsys fs, blk64_t blk)
+{
+ void *b;
+ errcode_t retval;
+
+ if (io_channel_discard_zeroes_data(fs->io)) {
+ retval = io_channel_discard(fs->io, blk, 1);
+ if (retval == 0)
+ return 0;
+ }
+
+ retval = ext2fs_get_memzero(fs->blocksize, &b);
+ if (retval)
+ return retval;
+
+ memset(b, 0, fs->blocksize);
+
+ retval = io_channel_write_blk64(fs->io, blk, 1, b);
+ if (retval)
+ goto out;
+
+out:
+ ext2fs_free_mem(&b);
+ return retval;
+}
+
static _BMAP_INLINE_ errcode_t block_ind_bmap(ext2_filsys fs, int flags,
blk_t ind, char *block_buf,
int *blocks_alloc,
@@ -72,6 +98,11 @@ static _BMAP_INLINE_ errcode_t block_ind_bmap(ext2_filsys fs, int flags,
block_buf + fs->blocksize, &b);
if (retval)
return retval;
+ if (flags & BMAP_UNINIT) {
+ retval = zero_block(fs, b);
+ if (retval)
+ return retval;
+ }
#ifdef WORDS_BIGENDIAN
((blk_t *) block_buf)[nr] = ext2fs_swab32(b);
@@ -214,10 +245,13 @@ static errcode_t extent_bmap(ext2_filsys fs, ext2_ino_t ino,
errcode_t retval = 0;
blk64_t blk64 = 0;
int alloc = 0;
+ int set_flags;
+
+ set_flags = bmap_flags & BMAP_UNINIT ? EXT2_EXTENT_SET_BMAP_UNINIT : 0;
if (bmap_flags & BMAP_SET) {
retval = ext2fs_extent_set_bmap(handle, block,
- *phys_blk, 0);
+ *phys_blk, set_flags);
return retval;
}
retval = ext2fs_extent_goto(handle, block);
@@ -254,7 +288,7 @@ got_block:
alloc++;
set_extent:
retval = ext2fs_extent_set_bmap(handle, block,
- blk64, 0);
+ blk64, set_flags);
if (retval)
return retval;
/* Update inode after setting extent */
@@ -336,6 +370,12 @@ errcode_t ext2fs_bmap2(ext2_filsys fs, ext2_ino_t ino, struct ext2_inode *inode,
goto done;
}
+ if ((bmap_flags & BMAP_SET) && (bmap_flags & BMAP_UNINIT)) {
+ retval = zero_block(fs, *phys_blk);
+ if (retval)
+ goto done;
+ }
+
if (block < EXT2_NDIR_BLOCKS) {
if (bmap_flags & BMAP_SET) {
b = *phys_blk;
@@ -351,6 +391,11 @@ errcode_t ext2fs_bmap2(ext2_filsys fs, ext2_ino_t ino, struct ext2_inode *inode,
retval = ext2fs_alloc_block(fs, b, block_buf, &b);
if (retval)
goto done;
+ if (bmap_flags & BMAP_UNINIT) {
+ retval = zero_block(fs, b);
+ if (retval)
+ goto done;
+ }
inode_bmap(inode, block) = b;
blocks_alloc++;
*phys_blk = b;
diff --git a/lib/ext2fs/ext2fs.h b/lib/ext2fs/ext2fs.h
index da518df..316e6f5 100644
--- a/lib/ext2fs/ext2fs.h
+++ b/lib/ext2fs/ext2fs.h
@@ -525,6 +525,7 @@ typedef struct ext2_icount *ext2_icount_t;
*/
#define BMAP_ALLOC 0x0001
#define BMAP_SET 0x0002
+#define BMAP_UNINIT 0x0004
/*
* Returned flags from ext2fs_bmap
--
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