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Message-Id: <11761304543898-git-send-email-jsipek@cs.sunysb.edu>
Date: Mon, 9 Apr 2007 10:53:59 -0400
From: "Josef 'Jeff' Sipek" <jsipek@...sunysb.edu>
To: linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org
Cc: akpm@...ux-foundation.org, Erez Zadok <ezk@...sunysb.edu>,
"Josef 'Jeff' Sipek" <jsipek@...sunysb.edu>
Subject: [PATCH 08/21] Unionfs: Introduce branch-id code
From: Erez Zadok <ezk@...sunysb.edu>
Each branch gets a unique ID, which helps during branch additions,
deletions, and changes, to locate where branches were moved to, and perform
proper reference-counting. This is useful even if the same directory was
added more than once to union.
Signed-off-by: Erez Zadok <ezk@...sunysb.edu>
Signed-off-by: Josef 'Jeff' Sipek <jsipek@...sunysb.edu>
---
fs/unionfs/commonfops.c | 62 +++++++++++++++++++++++++++++++++++++++++++++-
fs/unionfs/fanout.h | 22 ++++++++++++++++-
fs/unionfs/main.c | 1 +
fs/unionfs/union.h | 4 ++-
4 files changed, 85 insertions(+), 4 deletions(-)
diff --git a/fs/unionfs/commonfops.c b/fs/unionfs/commonfops.c
index aa7c75d..8d0f8d1 100644
--- a/fs/unionfs/commonfops.c
+++ b/fs/unionfs/commonfops.c
@@ -86,6 +86,31 @@ out:
return err;
}
+/*
+ * Find new index of matching branch with an open file, since branches could
+ * have been added/deleted causing the one with open files to shift.
+ *
+ * @file: current file whose branches may have changed
+ * @bindex: index of branch within current file (could be old branch)
+ * @new_sb: the new superblock which may have new branch IDs
+ * Returns index of newly found branch (0 or greater), -1 otherwise.
+ */
+static int find_new_branch_index(struct file *file, int bindex,
+ struct super_block *new_sb)
+{
+ int old_branch_id = UNIONFS_F(file)->saved_branch_ids[bindex];
+ int i;
+
+ for (i = 0; i < sbmax(new_sb); i++)
+ if (old_branch_id == branch_id(new_sb, i))
+ return i;
+ /*
+ * XXX: maybe we should BUG_ON if not found new branch index?
+ * (really that should never happen).
+ */
+ return -1;
+}
+
/* put all references held by upper struct file and free lower file pointer
* array
*/
@@ -93,6 +118,7 @@ static void cleanup_file(struct file *file)
{
int bindex, bstart, bend;
struct file **lf;
+ struct super_block *sb = file->f_dentry->d_sb;
lf = UNIONFS_F(file)->lower_files;
bstart = fbstart(file);
@@ -100,13 +126,29 @@ static void cleanup_file(struct file *file)
for (bindex = bstart; bindex <= bend; bindex++) {
if (unionfs_lower_file_idx(file, bindex)) {
- branchput(file->f_dentry->d_sb, bindex);
+ int i; /* holds (possibly) updated branch index */
+ i = find_new_branch_index(file, bindex, sb);
+ if (i < 0)
+ printk(KERN_ERR "unionfs: no supberlock for file %p\n",
+ file);
+ else {
+ unionfs_read_lock(sb);
+ branchput(sb, i);
+ unionfs_read_unlock(sb);
+ /* XXX: is it correct to use sb->s_root here? */
+ unionfs_mntput(sb->s_root, i);
+ /* XXX: mntget b/c fput below will call mntput */
+ unionfs_mntget(sb->s_root, bindex);
+ }
fput(unionfs_lower_file_idx(file, bindex));
}
}
UNIONFS_F(file)->lower_files = NULL;
kfree(lf);
+ kfree(UNIONFS_F(file)->saved_branch_ids);
+ /* set to NULL because caller needs to know if to kfree on error */
+ UNIONFS_F(file)->saved_branch_ids = NULL;
}
/* open all lower files for a given file */
@@ -270,6 +312,12 @@ int unionfs_file_revalidate(struct file *file, int willwrite)
err = -ENOMEM;
goto out;
}
+ size = sizeof(int) * sbmax(sb);
+ UNIONFS_F(file)->saved_branch_ids = kzalloc(size, GFP_KERNEL);
+ if (!UNIONFS_F(file)->saved_branch_ids) {
+ err = -ENOMEM;
+ goto out;
+ }
if (S_ISDIR(dentry->d_inode->i_mode)) {
/* We need to open all the files. */
@@ -297,8 +345,10 @@ int unionfs_file_revalidate(struct file *file, int willwrite)
}
out:
- if (err)
+ if (err) {
kfree(UNIONFS_F(file)->lower_files);
+ kfree(UNIONFS_F(file)->saved_branch_ids);
+ }
out_nofree:
unionfs_unlock_dentry(dentry);
unionfs_read_unlock(dentry->d_sb);
@@ -418,6 +468,12 @@ int unionfs_open(struct inode *inode, struct file *file)
err = -ENOMEM;
goto out;
}
+ size = sizeof(int) * sbmax(inode->i_sb);
+ UNIONFS_F(file)->saved_branch_ids = kzalloc(size, GFP_KERNEL);
+ if (!UNIONFS_F(file)->saved_branch_ids) {
+ err = -ENOMEM;
+ goto out;
+ }
dentry = file->f_dentry;
unionfs_lock_dentry(dentry);
@@ -456,6 +512,7 @@ int unionfs_open(struct inode *inode, struct file *file)
out:
if (err) {
kfree(UNIONFS_F(file)->lower_files);
+ kfree(UNIONFS_F(file)->saved_branch_ids);
kfree(UNIONFS_F(file));
}
out_nofree:
@@ -487,6 +544,7 @@ int unionfs_file_release(struct inode *inode, struct file *file)
}
}
kfree(fileinfo->lower_files);
+ kfree(fileinfo->saved_branch_ids);
if (fileinfo->rdstate) {
fileinfo->rdstate->access = jiffies;
diff --git a/fs/unionfs/fanout.h b/fs/unionfs/fanout.h
index e8c0fee..9e4a35f 100644
--- a/fs/unionfs/fanout.h
+++ b/fs/unionfs/fanout.h
@@ -32,12 +32,29 @@ static inline struct unionfs_inode_info *UNIONFS_I(const struct inode *inode)
#define sbstart(sb) 0
#define sbend(sb) (UNIONFS_SB(sb)->bend)
#define sbmax(sb) (UNIONFS_SB(sb)->bend + 1)
+#define sbhbid(sb) (UNIONFS_SB(sb)->high_branch_id)
/* File to private Data */
#define UNIONFS_F(file) ((struct unionfs_file_info *)((file)->private_data))
#define fbstart(file) (UNIONFS_F(file)->bstart)
#define fbend(file) (UNIONFS_F(file)->bend)
+/* macros to manipulate branch IDs in stored in our superblock */
+static inline int branch_id(struct super_block *sb, int index)
+{
+ return UNIONFS_SB(sb)->data[index].branch_id;
+}
+
+static inline void set_branch_id(struct super_block *sb, int index, int val)
+{
+ UNIONFS_SB(sb)->data[index].branch_id = val;
+}
+
+static inline void new_branch_id(struct super_block *sb, int index)
+{
+ set_branch_id(sb, index, ++UNIONFS_SB(sb)->high_branch_id);
+}
+
/* File to lower file. */
static inline struct file *unionfs_lower_file(const struct file *f)
{
@@ -52,11 +69,14 @@ static inline struct file *unionfs_lower_file_idx(const struct file *f, int inde
static inline void unionfs_set_lower_file_idx(struct file *f, int index, struct file *val)
{
UNIONFS_F(f)->lower_files[index] = val;
+ /* save branch ID (may be redundant?) */
+ UNIONFS_F(f)->saved_branch_ids[index] =
+ branch_id((f)->f_dentry->d_sb, index);
}
static inline void unionfs_set_lower_file(struct file *f, struct file *val)
{
- UNIONFS_F(f)->lower_files[fbstart(f)] = val;
+ unionfs_set_lower_file_idx((f), fbstart(f), (val));
}
/* Inode to lower inode. */
diff --git a/fs/unionfs/main.c b/fs/unionfs/main.c
index a37916d..ed264c7 100644
--- a/fs/unionfs/main.c
+++ b/fs/unionfs/main.c
@@ -515,6 +515,7 @@ static int unionfs_read_super(struct super_block *sb, void *raw_data,
UNIONFS_SB(sb)->bend = -1;
atomic_set(&UNIONFS_SB(sb)->generation, 1);
init_rwsem(&UNIONFS_SB(sb)->rwsem);
+ UNIONFS_SB(sb)->high_branch_id = -1; /* -1 == invalid branch ID */
hidden_root_info = unionfs_parse_options(sb, raw_data);
if (IS_ERR(hidden_root_info)) {
diff --git a/fs/unionfs/union.h b/fs/unionfs/union.h
index df9b8c0..7bd6306 100644
--- a/fs/unionfs/union.h
+++ b/fs/unionfs/union.h
@@ -80,6 +80,7 @@ struct unionfs_file_info {
struct unionfs_dir_state *rdstate;
struct file **lower_files;
+ int *saved_branch_ids; /* IDs of branches when file was opened */
};
/* unionfs inode data in memory */
@@ -123,6 +124,7 @@ struct unionfs_data {
struct super_block *sb;
atomic_t open_files; /* number of open files on branch */
int branchperms;
+ int branch_id; /* unique branch ID at re/mount time */
};
/* unionfs super-block data in memory */
@@ -131,7 +133,7 @@ struct unionfs_sb_info {
atomic_t generation;
struct rw_semaphore rwsem; /* protects access to data+id fields */
-
+ int high_branch_id; /* last unique branch ID given */
struct unionfs_data *data;
};
--
1.5.0.3.268.g3dda
-
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