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fanotify: infrastructure to add an remove marks on vfsmounts
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infrastructure work to add and remove marks on vfsmounts.  This should get
every set up except wiring the functions to the syscalls.

Signed-off-by: Eric Paris <eparis@redhat.com>
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Eric Paris committed Jul 28, 2010
1 parent 1c52906 commit 8882627
Showing 1 changed file with 133 additions and 52 deletions.
185 changes: 133 additions & 52 deletions fs/notify/fanotify/fanotify_user.c
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Original file line number Diff line number Diff line change
Expand Up @@ -295,112 +295,193 @@ static int fanotify_find_path(int dfd, const char __user *filename,
return ret;
}

static int fanotify_remove_mark(struct fsnotify_group *group,
struct inode *inode,
__u32 mask)
static void fanotify_update_object_mask(struct fsnotify_group *group,
struct inode *inode,
struct vfsmount *mnt,
struct fsnotify_mark *fsn_mark,
unsigned int flags,
__u32 mask)
{
struct fsnotify_mark *fsn_mark;
__u32 new_mask;

pr_debug("%s: group=%p inode=%p mask=%x\n", __func__,
group, inode, mask);
__u32 old_mask, new_mask;

fsn_mark = fsnotify_find_inode_mark(group, inode);
if (!fsn_mark)
return -ENOENT;
pr_debug("%s: group=%p inode=%p mnt=%p fsn_mark=%p flags=%x mask=%x\n",
__func__, group, inode, mnt, fsn_mark, flags, mask);

spin_lock(&fsn_mark->lock);
fsn_mark->mask &= ~mask;
old_mask = fsn_mark->mask;
if (flags & FAN_MARK_ADD)
fsn_mark->mask |= mask;
else if (flags & FAN_MARK_REMOVE)
fsn_mark->mask &= ~mask;
else
BUG();
new_mask = fsn_mark->mask;
spin_unlock(&fsn_mark->lock);

if (!new_mask)
fsnotify_destroy_mark(fsn_mark);

/* we made changes to a mask, update the group mask and the object mask
* so things happen quickly. */
if (old_mask != new_mask) {
__u32 dropped, do_object, do_group;

/* more bits in old than in new? */
dropped = (old_mask & ~new_mask);
/* more bits in this fsn_mark than the group? */
do_group = (new_mask & ~group->mask);

if (inode) {
/* more bits in this fsn_mark than the object's mask? */
do_object = (new_mask & ~inode->i_fsnotify_mask);
/* update the object with this new fsn_mark */
if (dropped || do_object)
fsnotify_recalc_inode_mask(inode);
} else if (mnt) {
/* more bits in this fsn_mark than the object's mask? */
do_object = (new_mask & ~mnt->mnt_fsnotify_mask);
/* update the object with this new fsn_mark */
if (dropped || do_object)
fsnotify_recalc_vfsmount_mask(mnt);
} else {
BUG();
}

/* update the group mask with the new mask */
if (dropped || do_group)
fsnotify_recalc_group_mask(group);
}
}

static int fanotify_remove_mark(struct fsnotify_group *group, struct inode *inode,
struct vfsmount *mnt, unsigned int flags, __u32 mask)
{
struct fsnotify_mark *fsn_mark = NULL;

BUG_ON(inode && mnt);
BUG_ON(!inode && !mnt);

if (inode)
fsn_mark = fsnotify_find_inode_mark(group, inode);
else if (mnt)
fsn_mark = fsnotify_find_vfsmount_mark(group, mnt);
else
fsnotify_recalc_inode_mask(inode);
BUG();

fsnotify_recalc_group_mask(group);
if (!fsn_mark)
return -ENOENT;

fanotify_update_object_mask(group, inode, mnt, fsn_mark, flags, mask);

/* matches the fsnotify_find_inode_mark() */
fsnotify_put_mark(fsn_mark);

return 0;
}

static int fanotify_add_mark(struct fsnotify_group *group,
struct inode *inode,
__u32 mask)
static struct fsnotify_mark *fanotify_add_vfsmount_mark(struct fsnotify_group *group,
struct vfsmount *mnt)
{
struct fsnotify_mark *fsn_mark;
__u32 old_mask, new_mask;
int ret;

pr_debug("%s: group=%p inode=%p mask=%x\n", __func__,
group, inode, mask);
fsn_mark = fsnotify_find_vfsmount_mark(group, mnt);
if (!fsn_mark) {
struct fsnotify_mark *new_fsn_mark;
int ret;

fsn_mark = ERR_PTR(-ENOMEM);
new_fsn_mark = kmem_cache_alloc(fanotify_mark_cache, GFP_KERNEL);
if (!new_fsn_mark)
goto out;

fsnotify_init_mark(new_fsn_mark, fanotify_free_mark);
ret = fsnotify_add_mark(new_fsn_mark, group, NULL, mnt, 0);
if (ret) {
fsn_mark = ERR_PTR(ret);
fanotify_free_mark(new_fsn_mark);
goto out;
}

fsn_mark = new_fsn_mark;
}
out:
return fsn_mark;
}

static struct fsnotify_mark *fanotify_add_inode_mark(struct fsnotify_group *group,
struct inode *inode)
{
struct fsnotify_mark *fsn_mark;

pr_debug("%s: group=%p inode=%p\n", __func__, group, inode);

fsn_mark = fsnotify_find_inode_mark(group, inode);
if (!fsn_mark) {
struct fsnotify_mark *new_fsn_mark;
int ret;

ret = -ENOMEM;
fsn_mark = ERR_PTR(-ENOMEM);
new_fsn_mark = kmem_cache_alloc(fanotify_mark_cache, GFP_KERNEL);
if (!new_fsn_mark)
goto out;

fsnotify_init_mark(new_fsn_mark, fanotify_free_mark);
ret = fsnotify_add_mark(new_fsn_mark, group, inode, NULL, 0);
if (ret) {
fsn_mark = ERR_PTR(ret);
fanotify_free_mark(new_fsn_mark);
goto out;
}

fsn_mark = new_fsn_mark;
}
out:
return fsn_mark;
}

ret = 0;
static int fanotify_add_mark(struct fsnotify_group *group, struct inode *inode,
struct vfsmount *mnt, unsigned int flags, __u32 mask)
{
struct fsnotify_mark *fsn_mark;

spin_lock(&fsn_mark->lock);
old_mask = fsn_mark->mask;
fsn_mark->mask |= mask;
new_mask = fsn_mark->mask;
spin_unlock(&fsn_mark->lock);
pr_debug("%s: group=%p inode=%p mnt=%p flags=%x mask=%x\n",
__func__, group, inode, mnt, flags, mask);

/* we made changes to a mask, update the group mask and the inode mask
* so things happen quickly. */
if (old_mask != new_mask) {
/* more bits in old than in new? */
int dropped = (old_mask & ~new_mask);
/* more bits in this mark than the inode's mask? */
int do_inode = (new_mask & ~inode->i_fsnotify_mask);
/* more bits in this mark than the group? */
int do_group = (new_mask & ~group->mask);
BUG_ON(inode && mnt);
BUG_ON(!inode && !mnt);

/* update the inode with this new mark */
if (dropped || do_inode)
fsnotify_recalc_inode_mask(inode);
if (inode)
fsn_mark = fanotify_add_inode_mark(group, inode);
else if (mnt)
fsn_mark = fanotify_add_vfsmount_mark(group, mnt);
else
BUG();

/* update the group mask with the new mask */
if (dropped || do_group)
fsnotify_recalc_group_mask(group);
}
if (IS_ERR(fsn_mark))
goto out;

fanotify_update_object_mask(group, inode, mnt, fsn_mark, flags, mask);

/* match the init or the find.... */
fsnotify_put_mark(fsn_mark);
out:
return ret;
return PTR_ERR(fsn_mark);
}

static int fanotify_update_mark(struct fsnotify_group *group,
struct inode *inode, int flags,
__u32 mask)
struct inode *inode, struct vfsmount *mnt,
int flags, __u32 mask)
{
pr_debug("%s: group=%p inode=%p flags=%x mask=%x\n", __func__,
group, inode, flags, mask);
pr_debug("%s: group=%p inode=%p mnt=%p flags=%x mask=%x\n",
__func__, group, inode, mnt, flags, mask);

BUG_ON(inode && mnt);
BUG_ON(!inode && !mnt);

if (flags & FAN_MARK_ADD)
fanotify_add_mark(group, inode, mask);
fanotify_add_mark(group, inode, mnt, flags, mask);
else if (flags & FAN_MARK_REMOVE)
fanotify_remove_mark(group, inode, mask);
fanotify_remove_mark(group, inode, mnt, flags, mask);
else
BUG();

Expand Down Expand Up @@ -502,7 +583,7 @@ SYSCALL_DEFINE(fanotify_mark)(int fanotify_fd, unsigned int flags,
group = filp->private_data;

/* create/update an inode mark */
ret = fanotify_update_mark(group, inode, flags, mask);
ret = fanotify_update_mark(group, inode, NULL, flags, mask);

path_put(&path);
fput_and_out:
Expand Down

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