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Message-Id: <11902770983349-git-send-email-htejun@gmail.com>
Date: Thu, 20 Sep 2007 17:31:38 +0900
From: Tejun Heo <htejun@...il.com>
To: ebiederm@...ssion.com, cornelia.huck@...ibm.com, greg@...ah.com,
stern@...land.harvard.edu, kay.sievers@...y.org,
linux-kernel@...r.kernel.org, htejun@...il.com
Cc: Tejun Heo <htejun@...il.com>
Subject: [PATCH 7/8] sysfs: implement batch error handling
Batch error handling is to be used with plugged creation. It
accumulates any error condition which happens under a plugged node and
let the user handle error once right before unplugging. This easily
replaces attribute group creation.
Batch error handling works by the following two mechanisms.
* When an error occurs, tree is walked toward the top and, if there
are plugged nodes which don't have plugged error recorded yet,
sd->s_batch_error is set before returning the error code.
* All interface funtions allow ERR_PTR value to be passed as
sysfs_dirent arguments and return -EBADF if that happens.
* After all the operations are complete, the user calls
sysfs_check_batch_error() on the plugged node (usually the top one)
which returns 0 if there hasn't been any error or error code of the
first error.
* The user unplugs or removes the node accordingly.
Signed-off-by: Tejun Heo <htejun@...il.com>
---
fs/sysfs/bin.c | 8 +++-
fs/sysfs/dir.c | 137 ++++++++++++++++++++++++++++++++++++++++++++++--
fs/sysfs/file.c | 12 ++++-
fs/sysfs/symlink.c | 7 +++
fs/sysfs/sysfs.h | 12 ++++-
include/linux/sysfs.h | 6 ++
6 files changed, 173 insertions(+), 9 deletions(-)
diff --git a/fs/sysfs/bin.c b/fs/sysfs/bin.c
index d6cc7b3..1f705d2 100644
--- a/fs/sysfs/bin.c
+++ b/fs/sysfs/bin.c
@@ -231,10 +231,16 @@ struct sysfs_dirent *sysfs_add_bin(struct sysfs_dirent *parent,
{
struct sysfs_dirent *sd;
+ /* for batch error handling */
+ if (IS_ERR(parent))
+ return ERR_PTR(-EBADF);
+
/* allocate and initialize */
sd = sysfs_new_dirent(name, mode, SYSFS_BIN);
- if (!sd)
+ if (!sd) {
+ sysfs_set_batch_error(parent, -ENOMEM);
return ERR_PTR(-ENOMEM);
+ }
sd->s_bin.ops = bops;
sd->s_bin.size = size;
diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
index 88ec749..f18da1b 100644
--- a/fs/sysfs/dir.c
+++ b/fs/sysfs/dir.c
@@ -305,7 +305,12 @@ void release_sysfs_dirent(struct sysfs_dirent * sd)
if (sd->s_flags & SYSFS_FLAG_LINK_NAME_FMT_COPIED)
kfree(sd->s_link.name_fmt);
- kfree(sd->s_iattr);
+ /* s_batch_error shares room with s_iattr. If plugged, it's
+ * s_batch_error; otherwise, s_iattr.
+ */
+ if (!(sd->s_flags & SYSFS_FLAG_PLUGGED))
+ kfree(sd->s_iattr);
+
sysfs_free_ino(sd->s_ino);
kmem_cache_free(sysfs_dir_cachep, sd);
@@ -722,6 +727,7 @@ struct sysfs_dirent *sysfs_insert_one(struct sysfs_dirent *parent,
if (rc) {
sysfs_put(sd);
+ sysfs_set_batch_error(parent, rc);
return ERR_PTR(rc);
}
@@ -804,6 +810,10 @@ struct sysfs_dirent *sysfs_find_child(struct sysfs_dirent *parent,
{
struct sysfs_dirent *sd;
+ /* for batch error handling */
+ if (IS_ERR(parent))
+ return ERR_PTR(-EBADF);
+
mutex_lock(&sysfs_mutex);
sd = sysfs_find_dirent(parent, name);
mutex_unlock(&sysfs_mutex);
@@ -837,10 +847,16 @@ struct sysfs_dirent *sysfs_add_dir(struct sysfs_dirent *parent,
{
struct sysfs_dirent *sd;
+ /* for plugged error handling */
+ if (IS_ERR(parent))
+ return ERR_PTR(-EBADF);
+
/* allocate and initialize */
sd = sysfs_new_dirent(name, mode, SYSFS_DIR);
- if (!sd)
+ if (!sd) {
+ sysfs_set_batch_error(parent, -ENOMEM);
return ERR_PTR(-ENOMEM);
+ }
sd->s_dir.data = data;
@@ -849,6 +865,71 @@ struct sysfs_dirent *sysfs_add_dir(struct sysfs_dirent *parent,
EXPORT_SYMBOL_GPL(sysfs_add_dir);
/**
+ * sysfs_set_batch_error - record batch error
+ * @sd: sysfs_dirent which failed operation
+ * @error: error value
+ *
+ * If @error is an error value, find all plugging ancestors and
+ * record batch error status if this is the first error in the
+ * subtree. Note that only the first error behind a plugged node
+ * is recorded.
+ *
+ * LOCKING:
+ * Kernel thread context (may sleep). Uses sysfs_mutex.
+ */
+void sysfs_set_batch_error(struct sysfs_dirent *sd, int error)
+{
+ if (!IS_ERR_VALUE(error))
+ return;
+
+ mutex_lock(&sysfs_mutex);
+
+ for ( ; sd; sd = sd->s_parent) {
+ if (!(sd->s_flags & SYSFS_FLAG_PLUGGED) || sd->s_batch_error) {
+ BUG_ON(sd->s_batch_error &&
+ !IS_ERR_VALUE(sd->s_batch_error));
+ continue;
+ }
+
+ /* s_iattr must be unused at this point */
+ BUG_ON(sd->s_iattr);
+ sd->s_batch_error = error;
+ }
+
+ mutex_unlock(&sysfs_mutex);
+}
+
+/**
+ * sysfs_check_batch_error - check batch error
+ * @sd: sysfs_dirent to check batch error for
+ *
+ * Check whether any error has occurred on a plugged node @sd and
+ * the nodes behind it.
+ *
+ * LOCKING:
+ * None.
+ *
+ * RETURNS:
+ * 0 if there hasn't been any batch error, -errno if it had one
+ * or more batch errors. -errno is from the first batch error.
+ */
+int sysfs_check_batch_error(struct sysfs_dirent *sd)
+{
+ int error = 0;
+
+ if (IS_ERR(sd))
+ return PTR_ERR(sd);
+
+ if (sd->s_batch_error) {
+ error = sd->s_batch_error;
+ BUG_ON(!IS_ERR_VALUE(error));
+ }
+
+ return error;
+}
+EXPORT_SYMBOL_GPL(sysfs_check_batch_error);
+
+/**
* sysfs_unplug - unplug a plugged sysfs_dirent
* @sd: sysfs_dirent to unplug
*
@@ -858,12 +939,19 @@ EXPORT_SYMBOL_GPL(sysfs_add_dir);
* userland.
*
* LOCKING:
- * Kernel thread context (may sleep). Uses sysfs_mutex.
+ * Kernel thread context (may sleep). Uses sysfs_op_mutex and
+ * sysfs_mutex.
*/
void sysfs_unplug(struct sysfs_dirent *sd)
{
struct sysfs_addrm_cxt acxt;
+ /* This happens when creation of the top node failed but the
+ * user want to ignore it. Do nothing.
+ */
+ if (IS_ERR(sd))
+ return;
+
/* Unplugging performs parent inode update delayed from
* add/removal. Also, sysfs_op_mutex grabbed by addrm_start
* guarantees renaming to see consistent plugged status.
@@ -876,6 +964,12 @@ void sysfs_unplug(struct sysfs_dirent *sd)
sd->s_flags &= ~SYSFS_FLAG_PLUGGED;
+ /* s_batch_error shares room with s_iattr, make sure
+ * it's NULL.
+ */
+ BUG_ON(sd->s_batch_error && !IS_ERR_VALUE(sd->s_batch_error));
+ sd->s_iattr = NULL;
+
if (parent_inode) {
parent_inode->i_ctime =
parent_inode->i_mtime = CURRENT_TIME;
@@ -1036,8 +1130,8 @@ void __sysfs_remove(struct sysfs_dirent *sd, int recurse)
struct sysfs_addrm_cxt acxt;
struct sysfs_dirent *cur, *next;
- /* noop on NULL */
- if (!sd)
+ /* noop on NULL and ERR_PTR, the latter is for batch error handling */
+ if (!sd || IS_ERR(sd))
return;
sysfs_addrm_start(&acxt);
@@ -1223,6 +1317,18 @@ static int sysfs_rcxt_get_dentries(struct sysfs_rename_context *rcxt,
struct dentry *old_dentry, *new_parent_dentry, *new_dentry;
int rc;
+ /* If sd is plugged currently and will stay plugged under the
+ * new parent, dentries are guaranteed to not exist and stay
+ * that way till rename is complete (op mutex released) and
+ * there's nothing to do regarding dentries.
+ *
+ * Changing plugged status by moving isn't allowed and this
+ * function will fail later if the user tries to do that.
+ */
+ if (sysfs_plugged(rent->sd, NULL) &&
+ sysfs_plugged(rent->sd, rent->new_parent))
+ return 0;
+
/* get old dentry */
old_dentry = sysfs_get_dentry(rent->sd);
if (IS_ERR(old_dentry))
@@ -1424,6 +1530,10 @@ int sysfs_rename(struct sysfs_dirent *sd, struct sysfs_dirent *new_parent,
struct sysfs_rcxt_rename_ent *rent;
int error;
+ /* for batch error handling */
+ if (IS_ERR(sd) || IS_ERR(new_parent))
+ return -EBADF;
+
mutex_lock(&sysfs_op_mutex);
if (!new_parent)
@@ -1463,6 +1573,12 @@ int sysfs_rename(struct sysfs_dirent *sd, struct sysfs_dirent *new_parent,
sysfs_link_sibling(rent->sd);
}
+ /* no dentry, no inode - this happens for plugged rename */
+ if (!rent->old_dentry) {
+ WARN_ON(rent->new_dentry);
+ continue;
+ }
+
/* update dcache and inode accordingly */
if (sysfs_type(rent->sd) == SYSFS_DIR) {
drop_nlink(rent->old_dentry->d_parent->d_inode);
@@ -1479,6 +1595,8 @@ int sysfs_rename(struct sysfs_dirent *sd, struct sysfs_dirent *new_parent,
sysfs_post_rename(&rcxt, error);
out:
mutex_unlock(&sysfs_op_mutex);
+ sysfs_set_batch_error(sd, error);
+ sysfs_set_batch_error(new_parent, error);
return error;
}
EXPORT_SYMBOL_GPL(sysfs_rename);
@@ -1498,11 +1616,17 @@ EXPORT_SYMBOL_GPL(sysfs_rename);
*/
int sysfs_chmod(struct sysfs_dirent *sd, mode_t mode)
{
- mode_t new_mode = (mode & S_IALLUGO) | (sd->s_mode & ~S_IALLUGO);
struct dentry *dentry = NULL;
struct inode *inode = NULL;
+ mode_t new_mode;
int rc = 0;
+ /* for batch error handling */
+ if (IS_ERR(sd))
+ return -EBADF;
+
+ new_mode = (mode & S_IALLUGO) | (sd->s_mode & ~S_IALLUGO);
+
mutex_lock(&sysfs_op_mutex);
/* If @sd is plugged, dentry and inode aren't there and can't
@@ -1537,6 +1661,7 @@ int sysfs_chmod(struct sysfs_dirent *sd, mode_t mode)
out_unlock_op:
mutex_unlock(&sysfs_op_mutex);
dput(dentry);
+ sysfs_set_batch_error(sd, rc);
return rc;
}
EXPORT_SYMBOL_GPL(sysfs_chmod);
diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
index 1d93940..3412732 100644
--- a/fs/sysfs/file.c
+++ b/fs/sysfs/file.c
@@ -498,6 +498,10 @@ void sysfs_notify_file(struct sysfs_dirent *sd)
{
struct sysfs_open_dirent *od;
+ /* for batch error handling */
+ if (IS_ERR(sd))
+ return;
+
BUG_ON(sysfs_type(sd) != SYSFS_FILE);
spin_lock(&sysfs_open_dirent_lock);
@@ -545,10 +549,16 @@ struct sysfs_dirent *sysfs_add_file(struct sysfs_dirent *parent,
{
struct sysfs_dirent *sd;
+ /* for batch error handling */
+ if (IS_ERR(parent))
+ return ERR_PTR(-EBADF);
+
/* allocate and initialize */
sd = sysfs_new_dirent(name, mode, SYSFS_FILE);
- if (!sd)
+ if (!sd) {
+ sysfs_set_batch_error(parent, -ENOMEM);
return ERR_PTR(-ENOMEM);
+ }
sd->s_file.ops = fops;
sd->s_file.data = data;
diff --git a/fs/sysfs/symlink.c b/fs/sysfs/symlink.c
index 53cc8a6..7e0fd89 100644
--- a/fs/sysfs/symlink.c
+++ b/fs/sysfs/symlink.c
@@ -217,6 +217,10 @@ struct sysfs_dirent *__sysfs_add_link(struct sysfs_dirent *parent,
struct sysfs_addrm_cxt acxt;
int rc;
+ /* for batch error handling */
+ if (IS_ERR(parent) || IS_ERR(target))
+ return ERR_PTR(-EBADF);
+
/* acquire locks early for link name formatting */
sysfs_addrm_start(&acxt);
@@ -280,6 +284,9 @@ struct sysfs_dirent *__sysfs_add_link(struct sysfs_dirent *parent,
kfree(name_fmt);
if (flags & SYSFS_FLAG_NAME_COPIED)
kfree(name);
+
+ sysfs_set_batch_error(parent, rc);
+ sysfs_set_batch_error(target, rc);
return ERR_PTR(rc);
}
diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h
index 51f346d..ec0b308 100644
--- a/fs/sysfs/sysfs.h
+++ b/fs/sysfs/sysfs.h
@@ -52,7 +52,15 @@ struct sysfs_dirent {
unsigned int s_flags;
ino_t s_ino;
umode_t s_mode;
- struct iattr *s_iattr;
+
+ /* Make s_iattr and s_batch_error share the room. This is
+ * okay because s_iattr is used only after a node is unplugged
+ * while s_batch_error is used only while a node is plugged.
+ */
+ union {
+ struct iattr *s_iattr;
+ int s_batch_error;
+ };
};
#define SD_DEACTIVATED_BIAS INT_MIN
@@ -120,6 +128,8 @@ struct sysfs_dirent *sysfs_get_dirent(struct sysfs_dirent *parent_sd,
const unsigned char *name);
struct sysfs_dirent *sysfs_new_dirent(const char *name, umode_t mode, int type);
+void sysfs_set_batch_error(struct sysfs_dirent *sd, int error);
+
void __sysfs_remove(struct sysfs_dirent *sd, int recurse);
void release_sysfs_dirent(struct sysfs_dirent *sd);
diff --git a/include/linux/sysfs.h b/include/linux/sysfs.h
index 5a8c9f1..a8dfc6b 100644
--- a/include/linux/sysfs.h
+++ b/include/linux/sysfs.h
@@ -64,6 +64,7 @@ struct sysfs_dirent *sysfs_add_bin(struct sysfs_dirent *parent,
struct sysfs_dirent *sysfs_add_link(struct sysfs_dirent *parent,
const char *name_fmt, mode_t mode,
struct sysfs_dirent *target);
+int sysfs_check_batch_error(struct sysfs_dirent *sd);
void sysfs_unplug(struct sysfs_dirent *sd);
struct sysfs_dirent *sysfs_find_child(struct sysfs_dirent *parent,
@@ -108,6 +109,11 @@ static inline struct sysfs_dirent *sysfs_add_link(struct sysfs_dirent *parent,
return NULL;
}
+static inline int sysfs_check_batch_error(struct sysfs_dirent *sd)
+{
+ return 0;
+}
+
static inline void sysfs_unplug(struct sysfs_dirent *sd)
{
}
--
1.5.0.3
-
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