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author | Nicolai Stange <nicstange@gmail.com> | 2017-10-31 00:15:47 +0100 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2017-11-07 20:25:02 +0100 |
commit | 7c8d469877b16d2c1cecf101a0abb7b218db85bc (patch) | |
tree | a6d2637db3d3d721e0079fd70e9f95ede449b942 | |
parent | 2ec16150179888b81717d1d3ce84e634f4736af2 (diff) | |
download | linux-stable-7c8d469877b16d2c1cecf101a0abb7b218db85bc.tar.gz linux-stable-7c8d469877b16d2c1cecf101a0abb7b218db85bc.tar.bz2 linux-stable-7c8d469877b16d2c1cecf101a0abb7b218db85bc.zip |
debugfs: add support for more elaborate ->d_fsdata
Currently, the user provided fops, "real_fops", are stored directly into
->d_fsdata.
In order to be able to store more per-file state and thus prepare for more
granular file removal protection, wrap the real_fops into a dynamically
allocated container struct, debugfs_fsdata.
A struct debugfs_fsdata gets allocated at file creation and freed from the
newly intoduced ->d_release().
Finally, move the implementation of debugfs_real_fops() out of the public
debugfs header such that struct debugfs_fsdata's declaration can be kept
private.
Signed-off-by: Nicolai Stange <nicstange@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r-- | fs/debugfs/file.c | 12 | ||||
-rw-r--r-- | fs/debugfs/inode.c | 22 | ||||
-rw-r--r-- | fs/debugfs/internal.h | 4 | ||||
-rw-r--r-- | include/linux/debugfs.h | 20 |
4 files changed, 38 insertions, 20 deletions
diff --git a/fs/debugfs/file.c b/fs/debugfs/file.c index 6dabc4a10396..b6f5ddab66bf 100644 --- a/fs/debugfs/file.c +++ b/fs/debugfs/file.c @@ -97,6 +97,18 @@ EXPORT_SYMBOL_GPL(debugfs_use_file_finish); #define F_DENTRY(filp) ((filp)->f_path.dentry) +const struct file_operations *debugfs_real_fops(const struct file *filp) + __must_hold(&debugfs_srcu) +{ + struct debugfs_fsdata *fsd = F_DENTRY(filp)->d_fsdata; + /* + * Neither the pointer to the struct file_operations, nor its + * contents ever change -- srcu_dereference() is not needed here. + */ + return fsd->real_fops; +} +EXPORT_SYMBOL_GPL(debugfs_real_fops); + static int open_proxy_open(struct inode *inode, struct file *filp) { const struct dentry *dentry = F_DENTRY(filp); diff --git a/fs/debugfs/inode.c b/fs/debugfs/inode.c index c59f015f386e..a9c3d3e9af39 100644 --- a/fs/debugfs/inode.c +++ b/fs/debugfs/inode.c @@ -185,6 +185,11 @@ static const struct super_operations debugfs_super_operations = { .evict_inode = debugfs_evict_inode, }; +static void debugfs_release_dentry(struct dentry *dentry) +{ + kfree(dentry->d_fsdata); +} + static struct vfsmount *debugfs_automount(struct path *path) { debugfs_automount_t f; @@ -194,6 +199,7 @@ static struct vfsmount *debugfs_automount(struct path *path) static const struct dentry_operations debugfs_dops = { .d_delete = always_delete_dentry, + .d_release = debugfs_release_dentry, .d_automount = debugfs_automount, }; @@ -341,24 +347,34 @@ static struct dentry *__debugfs_create_file(const char *name, umode_t mode, { struct dentry *dentry; struct inode *inode; + struct debugfs_fsdata *fsd; + + fsd = kmalloc(sizeof(*fsd), GFP_KERNEL); + if (!fsd) + return NULL; if (!(mode & S_IFMT)) mode |= S_IFREG; BUG_ON(!S_ISREG(mode)); dentry = start_creating(name, parent); - if (IS_ERR(dentry)) + if (IS_ERR(dentry)) { + kfree(fsd); return NULL; + } inode = debugfs_get_inode(dentry->d_sb); - if (unlikely(!inode)) + if (unlikely(!inode)) { + kfree(fsd); return failed_creating(dentry); + } inode->i_mode = mode; inode->i_private = data; inode->i_fop = proxy_fops; - dentry->d_fsdata = (void *)real_fops; + fsd->real_fops = real_fops; + dentry->d_fsdata = fsd; d_instantiate(dentry, inode); fsnotify_create(d_inode(dentry->d_parent), dentry); diff --git a/fs/debugfs/internal.h b/fs/debugfs/internal.h index b3e8443a1f47..512601eed3ce 100644 --- a/fs/debugfs/internal.h +++ b/fs/debugfs/internal.h @@ -19,4 +19,8 @@ extern const struct file_operations debugfs_noop_file_operations; extern const struct file_operations debugfs_open_proxy_file_operations; extern const struct file_operations debugfs_full_proxy_file_operations; +struct debugfs_fsdata { + const struct file_operations *real_fops; +}; + #endif /* _DEBUGFS_INTERNAL_H_ */ diff --git a/include/linux/debugfs.h b/include/linux/debugfs.h index b93efc8feecd..cbee5f4a02a3 100644 --- a/include/linux/debugfs.h +++ b/include/linux/debugfs.h @@ -45,23 +45,6 @@ extern struct dentry *arch_debugfs_dir; extern struct srcu_struct debugfs_srcu; -/** - * debugfs_real_fops - getter for the real file operation - * @filp: a pointer to a struct file - * - * Must only be called under the protection established by - * debugfs_use_file_start(). - */ -static inline const struct file_operations *debugfs_real_fops(const struct file *filp) - __must_hold(&debugfs_srcu) -{ - /* - * Neither the pointer to the struct file_operations, nor its - * contents ever change -- srcu_dereference() is not needed here. - */ - return filp->f_path.dentry->d_fsdata; -} - #define DEFINE_DEBUGFS_ATTRIBUTE(__fops, __get, __set, __fmt) \ static int __fops ## _open(struct inode *inode, struct file *file) \ { \ @@ -112,6 +95,9 @@ int debugfs_use_file_start(const struct dentry *dentry, int *srcu_idx) void debugfs_use_file_finish(int srcu_idx) __releases(&debugfs_srcu); +const struct file_operations *debugfs_real_fops(const struct file *filp) + __must_hold(&debugfs_srcu); + ssize_t debugfs_attr_read(struct file *file, char __user *buf, size_t len, loff_t *ppos); ssize_t debugfs_attr_write(struct file *file, const char __user *buf, |