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Subject[PATCH 2/4] VFS: Tell fsnotify what part of the file might have changed
From
Date
Signed-off-by: Alexey Zaytsev <alexey.zaytsev@gmail.com>
---
fs/compat.c | 2 +
fs/nfsd/vfs.c | 2 +
fs/open.c | 4 +++
fs/read_write.c | 4 +--
include/linux/fs.h | 14 +++++++++
include/linux/fsnotify.h | 68 ++++++++++++++++++++++++++++------------------
6 files changed, 64 insertions(+), 30 deletions(-)
diff --git a/fs/compat.c b/fs/compat.c
index c580c32..66eb689 100644
--- a/fs/compat.c
+++ b/fs/compat.c
@@ -1171,7 +1171,7 @@ out:
if (type == READ)
fsnotify_access(file);
else
- fsnotify_modify(file);
+ fsnotify_modify(file, pos - ret, ret);
}
return ret;
}
diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
index 184938f..d781014 100644
--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c
@@ -1035,7 +1035,7 @@ nfsd_vfs_write(struct svc_rqst *rqstp, struct svc_fh *fhp, struct file *file,
goto out_nfserr;
*cnt = host_err;
nfsdstats.io_write += host_err;
- fsnotify_modify(file);
+ fsnotify_modify(file, offset - host_err, host_err);

/* clear setuid/setgid flag after write */
if (inode->i_mode & (S_ISUID | S_ISGID))
diff --git a/fs/open.c b/fs/open.c
index 4197b9e..17b0d79 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -675,6 +675,10 @@ static struct file *__dentry_open(struct dentry *dentry, struct vfsmount *mnt,
f->f_path.mnt = mnt;
f->f_pos = 0;
f->f_op = fops_get(inode->i_fop);
+#ifdef CONFIG_FSNOTIFY
+ f->f_whatchanged.start = -1;
+ f->f_whatchanged.end = 0;
+#endif
file_sb_list_add(f, inode->i_sb);

error = security_dentry_open(f, cred);
diff --git a/fs/read_write.c b/fs/read_write.c
index 5d431ba..86c60c2 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -383,7 +383,7 @@ ssize_t vfs_write(struct file *file, const char __user *buf, size_t count, loff_
else
ret = do_sync_write(file, buf, count, pos);
if (ret > 0) {
- fsnotify_modify(file);
+ fsnotify_modify(file, (*pos) - ret, ret);
add_wchar(current, ret);
}
inc_syscw(current);
@@ -699,7 +699,7 @@ out:
if (type == READ)
fsnotify_access(file);
else
- fsnotify_modify(file);
+ fsnotify_modify(file, (*pos) - ret, ret);
}
return ret;
}
diff --git a/include/linux/fs.h b/include/linux/fs.h
index eedc00b..3337975 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -922,6 +922,16 @@ static inline int ra_has_index(struct file_ra_state *ra, pgoff_t index)
index < ra->start + ra->size);
}

+/*
+ * fsnotify wants to know, what might have changed during the file's lifetime.
+ * We maintain a single range, so it might include non-modified gaps, but this
+ * should work good enough for the majoroty of use cases, and the rest
+ * shold listen to individual 'modify' events. */
+struct fsnotify_range {
+ loff_t start; /* The beginning of the possibly modified area.*/
+ loff_t end; /* The first byte after the area. */
+};
+
#define FILE_MNT_WRITE_TAKEN 1
#define FILE_MNT_WRITE_RELEASED 2

@@ -965,6 +975,10 @@ struct file {
#ifdef CONFIG_DEBUG_WRITECOUNT
unsigned long f_mnt_write_state;
#endif
+
+#ifdef CONFIG_FSNOTIFY
+ struct fsnotify_range f_whatchanged;
+#endif
};

#define get_file(x) atomic_long_inc(&(x)->f_count)
diff --git a/include/linux/fsnotify.h b/include/linux/fsnotify.h
index 5c185fa..49e7788 100644
--- a/include/linux/fsnotify.h
+++ b/include/linux/fsnotify.h
@@ -26,12 +26,13 @@ static inline void fsnotify_d_instantiate(struct dentry *dentry,
}

/* Notify this dentry's parent about a child's events. */
-static inline int fsnotify_parent(struct path *path, struct dentry *dentry, __u32 mask)
+static inline int fsnotify_parent(struct path *path, struct dentry *dentry,
+ __u32 mask, struct fsnotify_range *range)
{
if (!dentry)
dentry = path->dentry;

- return __fsnotify_parent(path, dentry, mask);
+ return __fsnotify_parent(path, dentry, mask, range);
}

/* simple call site for access decisions */
@@ -53,11 +54,12 @@ static inline int fsnotify_perm(struct file *file, int mask)
else
BUG();

- ret = fsnotify_parent(path, NULL, fsnotify_mask);
+ ret = fsnotify_parent(path, NULL, fsnotify_mask, NULL);
if (ret)
return ret;

- return fsnotify(inode, fsnotify_mask, path, FSNOTIFY_EVENT_PATH, NULL, 0);
+ return fsnotify(inode, fsnotify_mask, path, FSNOTIFY_EVENT_PATH,
+ NULL, 0, NULL);
}

/*
@@ -78,7 +80,7 @@ static inline void fsnotify_d_move(struct dentry *dentry)
*/
static inline void fsnotify_link_count(struct inode *inode)
{
- fsnotify(inode, FS_ATTRIB, inode, FSNOTIFY_EVENT_INODE, NULL, 0);
+ fsnotify(inode, FS_ATTRIB, inode, FSNOTIFY_EVENT_INODE, NULL, 0, NULL);
}

/*
@@ -102,14 +104,17 @@ static inline void fsnotify_move(struct inode *old_dir, struct inode *new_dir,
new_dir_mask |= FS_ISDIR;
}

- fsnotify(old_dir, old_dir_mask, old_dir, FSNOTIFY_EVENT_INODE, old_name, fs_cookie);
- fsnotify(new_dir, new_dir_mask, new_dir, FSNOTIFY_EVENT_INODE, new_name, fs_cookie);
+ fsnotify(old_dir, old_dir_mask, old_dir, FSNOTIFY_EVENT_INODE,
+ old_name, fs_cookie, NULL);
+ fsnotify(new_dir, new_dir_mask, new_dir, FSNOTIFY_EVENT_INODE,
+ new_name, fs_cookie, NULL);

if (target)
fsnotify_link_count(target);

if (source)
- fsnotify(source, FS_MOVE_SELF, moved->d_inode, FSNOTIFY_EVENT_INODE, NULL, 0);
+ fsnotify(source, FS_MOVE_SELF, moved->d_inode, FSNOTIFY_EVENT_INODE,
+ NULL, 0, NULL);
audit_inode_child(moved, new_dir);
}

@@ -139,7 +144,7 @@ static inline void fsnotify_nameremove(struct dentry *dentry, int isdir)
if (isdir)
mask |= FS_ISDIR;

- fsnotify_parent(NULL, dentry, mask);
+ fsnotify_parent(NULL, dentry, mask, NULL);
}

/*
@@ -147,7 +152,7 @@ static inline void fsnotify_nameremove(struct dentry *dentry, int isdir)
*/
static inline void fsnotify_inoderemove(struct inode *inode)
{
- fsnotify(inode, FS_DELETE_SELF, inode, FSNOTIFY_EVENT_INODE, NULL, 0);
+ fsnotify(inode, FS_DELETE_SELF, inode, FSNOTIFY_EVENT_INODE, NULL, 0, NULL);
__fsnotify_inode_delete(inode);
}

@@ -158,7 +163,8 @@ static inline void fsnotify_create(struct inode *inode, struct dentry *dentry)
{
audit_inode_child(dentry, inode);

- fsnotify(inode, FS_CREATE, dentry->d_inode, FSNOTIFY_EVENT_INODE, dentry->d_name.name, 0);
+ fsnotify(inode, FS_CREATE, dentry->d_inode, FSNOTIFY_EVENT_INODE,
+ dentry->d_name.name, 0, NULL);
}

/*
@@ -171,7 +177,8 @@ static inline void fsnotify_link(struct inode *dir, struct inode *inode, struct
fsnotify_link_count(inode);
audit_inode_child(new_dentry, dir);

- fsnotify(dir, FS_CREATE, inode, FSNOTIFY_EVENT_INODE, new_dentry->d_name.name, 0);
+ fsnotify(dir, FS_CREATE, inode, FSNOTIFY_EVENT_INODE,
+ new_dentry->d_name.name, 0, NULL);
}

/*
@@ -184,7 +191,8 @@ static inline void fsnotify_mkdir(struct inode *inode, struct dentry *dentry)

audit_inode_child(dentry, inode);

- fsnotify(inode, mask, d_inode, FSNOTIFY_EVENT_INODE, dentry->d_name.name, 0);
+ fsnotify(inode, mask, d_inode, FSNOTIFY_EVENT_INODE,
+ dentry->d_name.name, 0, NULL);
}

/*
@@ -200,26 +208,33 @@ static inline void fsnotify_access(struct file *file)
mask |= FS_ISDIR;

if (!(file->f_mode & FMODE_NONOTIFY)) {
- fsnotify_parent(path, NULL, mask);
- fsnotify(inode, mask, path, FSNOTIFY_EVENT_PATH, NULL, 0);
+ fsnotify_parent(path, NULL, mask, NULL);
+ fsnotify(inode, mask, path, FSNOTIFY_EVENT_PATH, NULL, 0, NULL);
}
}

+
+
/*
* fsnotify_modify - file was modified
*/
-static inline void fsnotify_modify(struct file *file)
+static inline void fsnotify_modify(struct file *file, loff_t original, size_t count)
{
struct path *path = &file->f_path;
struct inode *inode = path->dentry->d_inode;
__u32 mask = FS_MODIFY;
+ struct fsnotify_range range = {
+ .start = original,
+ .end = original + count,
+ };

+ fsnotify_update_range(&file->f_whatchanged, &range);
if (S_ISDIR(inode->i_mode))
mask |= FS_ISDIR;

if (!(file->f_mode & FMODE_NONOTIFY)) {
- fsnotify_parent(path, NULL, mask);
- fsnotify(inode, mask, path, FSNOTIFY_EVENT_PATH, NULL, 0);
+ fsnotify_parent(path, NULL, mask, &range);
+ fsnotify(inode, mask, path, FSNOTIFY_EVENT_PATH, NULL, 0, &range);
}
}

@@ -238,8 +253,8 @@ static inline void fsnotify_open(struct file *file)
/* FMODE_NONOTIFY must never be set from user */
file->f_mode &= ~FMODE_NONOTIFY;

- fsnotify_parent(path, NULL, mask);
- fsnotify(inode, mask, path, FSNOTIFY_EVENT_PATH, NULL, 0);
+ fsnotify_parent(path, NULL, mask, NULL);
+ fsnotify(inode, mask, path, FSNOTIFY_EVENT_PATH, NULL, 0, NULL);
}

/*
@@ -256,8 +271,9 @@ static inline void fsnotify_close(struct file *file)
mask |= FS_ISDIR;

if (!(file->f_mode & FMODE_NONOTIFY)) {
- fsnotify_parent(path, NULL, mask);
- fsnotify(inode, mask, path, FSNOTIFY_EVENT_PATH, NULL, 0);
+ fsnotify_parent(path, NULL, mask, &file->f_whatchanged);
+ fsnotify(inode, mask, path, FSNOTIFY_EVENT_PATH,
+ NULL, 0, &file->f_whatchanged);
}
}

@@ -272,8 +288,8 @@ static inline void fsnotify_xattr(struct dentry *dentry)
if (S_ISDIR(inode->i_mode))
mask |= FS_ISDIR;

- fsnotify_parent(NULL, dentry, mask);
- fsnotify(inode, mask, inode, FSNOTIFY_EVENT_INODE, NULL, 0);
+ fsnotify_parent(NULL, dentry, mask, NULL);
+ fsnotify(inode, mask, inode, FSNOTIFY_EVENT_INODE, NULL, 0, NULL);
}

/*
@@ -307,8 +323,8 @@ static inline void fsnotify_change(struct dentry *dentry, unsigned int ia_valid)
if (S_ISDIR(inode->i_mode))
mask |= FS_ISDIR;

- fsnotify_parent(NULL, dentry, mask);
- fsnotify(inode, mask, inode, FSNOTIFY_EVENT_INODE, NULL, 0);
+ fsnotify_parent(NULL, dentry, mask, NULL);
+ fsnotify(inode, mask, inode, FSNOTIFY_EVENT_INODE, NULL, 0, NULL);
}
}



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