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Date: Tue, 7 Jun 2011 18:07:30 +0300
From: amir73il@...rs.sourceforge.net
To: linux-ext4@...r.kernel.org
Cc: tytso@....edu, lczerner@...hat.com,
Amir Goldstein <amir73il@...rs.sf.net>,
Yongqiang Yang <xiaoqiangnk@...il.com>
Subject: [PATCH v1 03/36] ext4: snapshot hooks - inside JBD hooks
From: Amir Goldstein <amir73il@...rs.sf.net>
Before every metadata buffer write, the journal API is called,
namely, one of the ext4_journal_get_XXX_access() functions.
We use these journal hooks to call the snapshot API, namely
ext4_snapshot_get_XXX_access(), to COW the metadata buffer before
it is modified for the first time.
Signed-off-by: Amir Goldstein <amir73il@...rs.sf.net>
Signed-off-by: Yongqiang Yang <xiaoqiangnk@...il.com>
---
fs/ext4/ext4_jbd2.c | 9 ++++++-
fs/ext4/ext4_jbd2.h | 15 ++++++++++---
fs/ext4/extents.c | 3 +-
fs/ext4/inode.c | 22 ++++++++++++++------
fs/ext4/move_extent.c | 3 +-
fs/ext4/snapshot.h | 51 +++++++++++++++++++++++++++++++++++++++++++++++++
6 files changed, 88 insertions(+), 15 deletions(-)
diff --git a/fs/ext4/ext4_jbd2.c b/fs/ext4/ext4_jbd2.c
index 560020d..833969b 100644
--- a/fs/ext4/ext4_jbd2.c
+++ b/fs/ext4/ext4_jbd2.c
@@ -23,13 +23,16 @@ int __ext4_journal_get_undo_access(const char *where, unsigned int line,
return err;
}
-int __ext4_journal_get_write_access(const char *where, unsigned int line,
- handle_t *handle, struct buffer_head *bh)
+int __ext4_journal_get_write_access_inode(const char *where, unsigned int line,
+ handle_t *handle, struct inode *inode,
+ struct buffer_head *bh, int exclude)
{
int err = 0;
if (ext4_handle_valid(handle)) {
err = jbd2_journal_get_write_access(handle, bh);
+ if (!err && !exclude)
+ err = ext4_snapshot_get_write_access(handle, inode, bh);
if (err)
ext4_journal_abort_handle(where, line, __func__, bh,
handle, err);
@@ -111,6 +114,8 @@ int __ext4_journal_get_create_access(const char *where, unsigned int line,
if (ext4_handle_valid(handle)) {
err = jbd2_journal_get_create_access(handle, bh);
+ if (!err)
+ err = ext4_snapshot_get_create_access(handle, bh);
if (err)
ext4_journal_abort_handle(where, line, __func__,
bh, handle, err);
diff --git a/fs/ext4/ext4_jbd2.h b/fs/ext4/ext4_jbd2.h
index 3da2092..ca6e135 100644
--- a/fs/ext4/ext4_jbd2.h
+++ b/fs/ext4/ext4_jbd2.h
@@ -132,9 +132,9 @@ void ext4_journal_abort_handle(const char *caller, unsigned int line,
int __ext4_journal_get_undo_access(const char *where, unsigned int line,
handle_t *handle, struct buffer_head *bh);
-int __ext4_journal_get_write_access(const char *where, unsigned int line,
- handle_t *handle, struct buffer_head *bh);
-
+int __ext4_journal_get_write_access_inode(const char *where, unsigned int line,
+ handle_t *handle, struct inode *inode,
+ struct buffer_head *bh, int exclude);
int __ext4_forget(const char *where, unsigned int line, handle_t *handle,
int is_metadata, struct inode *inode,
struct buffer_head *bh, ext4_fsblk_t blocknr);
@@ -151,8 +151,15 @@ int __ext4_handle_dirty_super(const char *where, unsigned int line,
#define ext4_journal_get_undo_access(handle, bh) \
__ext4_journal_get_undo_access(__func__, __LINE__, (handle), (bh))
+#define ext4_journal_get_write_access_exclude(handle, bh) \
+ __ext4_journal_get_write_access_inode(__func__, __LINE__, \
+ (handle), NULL, (bh), 1)
#define ext4_journal_get_write_access(handle, bh) \
- __ext4_journal_get_write_access(__func__, __LINE__, (handle), (bh))
+ __ext4_journal_get_write_access_inode(__func__, __LINE__, \
+ (handle), NULL, (bh), 0)
+#define ext4_journal_get_write_access_inode(handle, inode, bh) \
+ __ext4_journal_get_write_access_inode(__func__, __LINE__, \
+ (handle), (inode), (bh), 0)
#define ext4_forget(handle, is_metadata, inode, bh, block_nr) \
__ext4_forget(__func__, __LINE__, (handle), (is_metadata), (inode), \
(bh), (block_nr))
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index 7598224..6f0a711 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -79,7 +79,8 @@ static int ext4_ext_get_access(handle_t *handle, struct inode *inode,
{
if (path->p_bh) {
/* path points to block */
- return ext4_journal_get_write_access(handle, path->p_bh);
+ return ext4_journal_get_write_access_inode(handle,
+ inode, path->p_bh);
}
/* path points to leaf/index in inode body */
/* we use in-core data, no need to protect them */
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 9dbd806..80e3393 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -874,7 +874,8 @@ static int ext4_splice_branch(handle_t *handle, struct inode *inode,
*/
if (where->bh) {
BUFFER_TRACE(where->bh, "get_write_access");
- err = ext4_journal_get_write_access(handle, where->bh);
+ err = ext4_journal_get_write_access_inode(handle, inode,
+ where->bh);
if (err)
goto err_out;
}
@@ -4149,7 +4150,8 @@ static int ext4_clear_blocks(handle_t *handle, struct inode *inode,
goto out_err;
if (bh) {
BUFFER_TRACE(bh, "retaking write access");
- err = ext4_journal_get_write_access(handle, bh);
+ err = ext4_journal_get_write_access_inode(handle,
+ inode, bh);
if (unlikely(err))
goto out_err;
}
@@ -4200,7 +4202,8 @@ static void ext4_free_data(handle_t *handle, struct inode *inode,
if (this_bh) { /* For indirect block */
BUFFER_TRACE(this_bh, "get_write_access");
- err = ext4_journal_get_write_access(handle, this_bh);
+ err = ext4_journal_get_write_access_inode(handle, inode,
+ this_bh);
/* Important: if we can't update the indirect pointers
* to the blocks, we can't free them. */
if (err)
@@ -4363,8 +4366,8 @@ static void ext4_free_branches(handle_t *handle, struct inode *inode,
* pointed to by an indirect block: journal it
*/
BUFFER_TRACE(parent_bh, "get_write_access");
- if (!ext4_journal_get_write_access(handle,
- parent_bh)){
+ if (!ext4_journal_get_write_access_inode(
+ handle, inode, parent_bh)){
*p = 0;
BUFFER_TRACE(parent_bh,
"call ext4_handle_dirty_metadata");
@@ -4741,9 +4744,14 @@ has_buffer:
int ext4_get_inode_loc(struct inode *inode, struct ext4_iloc *iloc)
{
- /* We have all inode data except xattrs in memory here. */
- return __ext4_get_inode_loc(inode, iloc,
+ int in_mem = (!EXT4_SNAPSHOTS(inode->i_sb) &&
!ext4_test_inode_state(inode, EXT4_STATE_XATTR));
+
+ /*
+ * We have all inode's data except xattrs in memory here,
+ * but we must always read-in the entire inode block for COW.
+ */
+ return __ext4_get_inode_loc(inode, iloc, in_mem);
}
void ext4_set_inode_flags(struct inode *inode)
diff --git a/fs/ext4/move_extent.c b/fs/ext4/move_extent.c
index b9f3e78..ad5409a 100644
--- a/fs/ext4/move_extent.c
+++ b/fs/ext4/move_extent.c
@@ -421,7 +421,8 @@ mext_insert_extents(handle_t *handle, struct inode *orig_inode,
if (depth) {
/* Register to journal */
- ret = ext4_journal_get_write_access(handle, orig_path->p_bh);
+ ret = ext4_journal_get_write_access_inode(handle,
+ orig_inode, orig_path->p_bh);
if (ret)
return ret;
}
diff --git a/fs/ext4/snapshot.h b/fs/ext4/snapshot.h
index d0c985b..54241b9 100644
--- a/fs/ext4/snapshot.h
+++ b/fs/ext4/snapshot.h
@@ -145,6 +145,57 @@ static inline int EXT4_SNAPSHOTS(struct super_block *sb)
* Block access functions
*/
+/*
+ * get_write_access() is called before writing to a metadata block
+ * if @inode is not NULL, then this is an inode's indirect block
+ * otherwise, this is a file system global metadata block
+ *
+ * Return values:
+ * = 0 - block was COWed or doesn't need to be COWed
+ * < 0 - error
+ */
+static inline int ext4_snapshot_get_write_access(handle_t *handle,
+ struct inode *inode, struct buffer_head *bh)
+{
+ struct super_block *sb;
+
+ sb = handle->h_transaction->t_journal->j_private;
+ if (!EXT4_SNAPSHOTS(sb))
+ return 0;
+
+ return ext4_snapshot_cow(handle, inode, bh->b_blocknr, bh, 1);
+}
+
+/*
+ * get_create_access() is called after allocating a new metadata block
+ *
+ * Return values:
+ * = 0 - block was COWed or doesn't need to be COWed
+ * < 0 - error
+ */
+static inline int ext4_snapshot_get_create_access(handle_t *handle,
+ struct buffer_head *bh)
+{
+ struct super_block *sb;
+ int err;
+
+ sb = handle->h_transaction->t_journal->j_private;
+ if (!EXT4_SNAPSHOTS(sb))
+ return 0;
+
+ /* Should block be COWed? */
+ err = ext4_snapshot_cow(handle, NULL, bh->b_blocknr, bh, 0);
+ /*
+ * A new block shouldn't need to be COWed if get_delete_access() was
+ * called for all deleted blocks. However, it may need to be COWed
+ * if fsck was run and if it had freed some blocks without moving them
+ * to snapshot. In the latter case, -EIO will be returned.
+ */
+ if (err > 0)
+ err = -EIO;
+ return err;
+}
+
/* snapshot_ctl.c */
--
1.7.4.1
--
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