cregit-Linux how code gets into the kernel

Release 4.10 fs/notify/dnotify/dnotify.c

 * Directory notifications for Linux.
 * Copyright (C) 2000,2001,2002 Stephen Rothwell
 * Copyright (C) 2009 Eric Paris <Red Hat Inc>
 * dnotify was largly rewritten to use the new fsnotify infrastructure
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the
 * Free Software Foundation; either version 2, or (at your option) any
 * later version.
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * General Public License for more details.
#include <linux/fs.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/dnotify.h>
#include <linux/init.h>
#include <linux/spinlock.h>
#include <linux/slab.h>
#include <linux/fdtable.h>
#include <linux/fsnotify_backend.h>

int dir_notify_enable __read_mostly = 1;

static struct kmem_cache *dnotify_struct_cache __read_mostly;

static struct kmem_cache *dnotify_mark_cache __read_mostly;

static struct fsnotify_group *dnotify_group __read_mostly;

 * dnotify will attach one of these to each inode (i_fsnotify_marks) which
 * is being watched by dnotify.  If multiple userspace applications are watching
 * the same directory with dnotify their information is chained in dn

struct dnotify_mark {
struct fsnotify_mark fsn_mark;
struct dnotify_struct *dn;

 * When a process starts or stops watching an inode the set of events which
 * dnotify cares about for that inode may change.  This function runs the
 * list of everything receiving dnotify events about this directory and calculates
 * the set of all those events.  After it updates what dnotify is interested in
 * it calls the fsnotify function so it can update the set of all events relevant
 * to this inode.

static void dnotify_recalc_inode_mask(struct fsnotify_mark *fsn_mark) { __u32 new_mask, old_mask; struct dnotify_struct *dn; struct dnotify_mark *dn_mark = container_of(fsn_mark, struct dnotify_mark, fsn_mark); assert_spin_locked(&fsn_mark->lock); old_mask = fsn_mark->mask; new_mask = 0; for (dn = dn_mark->dn; dn != NULL; dn = dn->dn_next) new_mask |= (dn->dn_mask & ~FS_DN_MULTISHOT); fsnotify_set_mark_mask_locked(fsn_mark, new_mask); if (old_mask == new_mask) return; if (fsn_mark->inode) fsnotify_recalc_inode_mask(fsn_mark->inode); }


eric pariseric paris6559.09%480.00%

/* * Mains fsnotify call where events are delivered to dnotify. * Find the dnotify mark on the relevant inode, run the list of dnotify structs * on that mark and determine which of them has expressed interest in receiving * events of this type. When found send the correct process and signal and * destroy the dnotify struct if it was not registered to receive multiple * events. */
static int dnotify_handle_event(struct fsnotify_group *group, struct inode *inode, struct fsnotify_mark *inode_mark, struct fsnotify_mark *vfsmount_mark, u32 mask, const void *data, int data_type, const unsigned char *file_name, u32 cookie) { struct dnotify_mark *dn_mark; struct dnotify_struct *dn; struct dnotify_struct **prev; struct fown_struct *fown; __u32 test_mask = mask & ~FS_EVENT_ON_CHILD; /* not a dir, dnotify doesn't care */ if (!S_ISDIR(inode->i_mode)) return 0; BUG_ON(vfsmount_mark); dn_mark = container_of(inode_mark, struct dnotify_mark, fsn_mark); spin_lock(&inode_mark->lock); prev = &dn_mark->dn; while ((dn = *prev) != NULL) { if ((dn->dn_mask & test_mask) == 0) { prev = &dn->dn_next; continue; } fown = &dn->dn_filp->f_owner; send_sigio(fown, dn->dn_fd, POLL_MSG); if (dn->dn_mask & FS_DN_MULTISHOT) prev = &dn->dn_next; else { *prev = dn->dn_next; kmem_cache_free(dnotify_struct_cache, dn); dnotify_recalc_inode_mask(inode_mark); } } spin_unlock(&inode_mark->lock); return 0; }


eric pariseric paris10245.54%436.36%
stephen rothwellstephen rothwell7232.14%19.09%
jan karajan kara3616.07%327.27%
andreas gruenbacherandreas gruenbacher94.02%19.09%
andrew mortonandrew morton41.79%19.09%
al viroal viro10.45%19.09%

static void dnotify_free_mark(struct fsnotify_mark *fsn_mark) { struct dnotify_mark *dn_mark = container_of(fsn_mark, struct dnotify_mark, fsn_mark); BUG_ON(dn_mark->dn); kmem_cache_free(dnotify_mark_cache, dn_mark); }


eric pariseric paris40100.00%3100.00%

static struct fsnotify_ops dnotify_fsnotify_ops = { .handle_event = dnotify_handle_event, }; /* * Called every time a file is closed. Looks first for a dnotify mark on the * inode. If one is found run all of the ->dn structures attached to that * mark for one relevant to this process closing the file and remove that * dnotify_struct. If that was the last dnotify_struct also remove the * fsnotify_mark. */
void dnotify_flush(struct file *filp, fl_owner_t id) { struct fsnotify_mark *fsn_mark; struct dnotify_mark *dn_mark; struct dnotify_struct *dn; struct dnotify_struct **prev; struct inode *inode; bool free = false; inode = file_inode(filp); if (!S_ISDIR(inode->i_mode)) return; fsn_mark = fsnotify_find_inode_mark(dnotify_group, inode); if (!fsn_mark) return; dn_mark = container_of(fsn_mark, struct dnotify_mark, fsn_mark); mutex_lock(&dnotify_group->mark_mutex); spin_lock(&fsn_mark->lock); prev = &dn_mark->dn; while ((dn = *prev) != NULL) { if ((dn->dn_owner == id) && (dn->dn_filp == filp)) { *prev = dn->dn_next; kmem_cache_free(dnotify_struct_cache, dn); dnotify_recalc_inode_mask(fsn_mark); break; } prev = &dn->dn_next; } spin_unlock(&fsn_mark->lock); /* nothing else could have found us thanks to the dnotify_groups mark_mutex */ if (dn_mark->dn == NULL) { fsnotify_detach_mark(fsn_mark); free = true; } mutex_unlock(&dnotify_group->mark_mutex); if (free) fsnotify_free_mark(fsn_mark); fsnotify_put_mark(fsn_mark); }


eric pariseric paris19186.04%457.14%
jan karajan kara219.46%114.29%
lino sanfilippolino sanfilippo73.15%114.29%
al viroal viro31.35%114.29%

/* this conversion is done only at watch creation */
static __u32 convert_arg(unsigned long arg) { __u32 new_mask = FS_EVENT_ON_CHILD; if (arg & DN_MULTISHOT) new_mask |= FS_DN_MULTISHOT; if (arg & DN_DELETE) new_mask |= (FS_DELETE | FS_MOVED_FROM); if (arg & DN_MODIFY) new_mask |= FS_MODIFY; if (arg & DN_ACCESS) new_mask |= FS_ACCESS; if (arg & DN_ATTRIB) new_mask |= FS_ATTRIB; if (arg & DN_RENAME) new_mask |= FS_DN_RENAME; if (arg & DN_CREATE) new_mask |= (FS_CREATE | FS_MOVED_TO); return new_mask; }


eric pariseric paris96100.00%1100.00%

/* * If multiple processes watch the same inode with dnotify there is only one * dnotify mark in inode->i_fsnotify_marks but we chain a dnotify_struct * onto that mark. This function either attaches the new dnotify_struct onto * that list, or it |= the mask onto an existing dnofiy_struct. */
static int attach_dn(struct dnotify_struct *dn, struct dnotify_mark *dn_mark, fl_owner_t id, int fd, struct file *filp, __u32 mask) { struct dnotify_struct *odn; odn = dn_mark->dn; while (odn != NULL) { /* adding more events to existing dnofiy_struct? */ if ((odn->dn_owner == id) && (odn->dn_filp == filp)) { odn->dn_fd = fd; odn->dn_mask |= mask; return -EEXIST; } odn = odn->dn_next; } dn->dn_mask = mask; dn->dn_fd = fd; dn->dn_filp = filp; dn->dn_owner = id; dn->dn_next = dn_mark->dn; dn_mark->dn = dn; return 0; }


eric pariseric paris13097.74%266.67%

/* * When a process calls fcntl to attach a dnotify watch to a directory it ends * up here. Allocate both a mark for fsnotify to add and a dnotify_struct to be * attached to the fsnotify_mark. */
int fcntl_dirnotify(int fd, struct file *filp, unsigned long arg) { struct dnotify_mark *new_dn_mark, *dn_mark; struct fsnotify_mark *new_fsn_mark, *fsn_mark; struct dnotify_struct *dn; struct inode *inode; fl_owner_t id = current->files; struct file *f; int destroy = 0, error = 0; __u32 mask; /* we use these to tell if we need to kfree */ new_fsn_mark = NULL; dn = NULL; if (!dir_notify_enable) { error = -EINVAL; goto out_err; } /* a 0 mask means we are explicitly removing the watch */ if ((arg & ~DN_MULTISHOT) == 0) { dnotify_flush(filp, id); error = 0; goto out_err; } /* dnotify only works on directories */ inode = file_inode(filp); if (!S_ISDIR(inode->i_mode)) { error = -ENOTDIR; goto out_err; } /* expect most fcntl to add new rather than augment old */ dn = kmem_cache_alloc(dnotify_struct_cache, GFP_KERNEL); if (!dn) { error = -ENOMEM; goto out_err; } /* new fsnotify mark, we expect most fcntl calls to add a new mark */ new_dn_mark = kmem_cache_alloc(dnotify_mark_cache, GFP_KERNEL); if (!new_dn_mark) { error = -ENOMEM; goto out_err; } /* convert the userspace DN_* "arg" to the internal FS_* defines in fsnotify */ mask = convert_arg(arg); /* set up the new_fsn_mark and new_dn_mark */ new_fsn_mark = &new_dn_mark->fsn_mark; fsnotify_init_mark(new_fsn_mark, dnotify_free_mark); new_fsn_mark->mask = mask; new_dn_mark->dn = NULL; /* this is needed to prevent the fcntl/close race described below */ mutex_lock(&dnotify_group->mark_mutex); /* add the new_fsn_mark or find an old one. */ fsn_mark = fsnotify_find_inode_mark(dnotify_group, inode); if (fsn_mark) { dn_mark = container_of(fsn_mark, struct dnotify_mark, fsn_mark); spin_lock(&fsn_mark->lock); } else { fsnotify_add_mark_locked(new_fsn_mark, dnotify_group, inode, NULL, 0); spin_lock(&new_fsn_mark->lock); fsn_mark = new_fsn_mark; dn_mark = new_dn_mark; /* we used new_fsn_mark, so don't free it */ new_fsn_mark = NULL; } rcu_read_lock(); f = fcheck(fd); rcu_read_unlock(); /* if (f != filp) means that we lost a race and another task/thread * actually closed the fd we are still playing with before we grabbed * the dnotify_groups mark_mutex and fsn_mark->lock. Since closing the * fd is the only time we clean up the marks we need to get our mark * off the list. */ if (f != filp) { /* if we added ourselves, shoot ourselves, it's possible that * the flush actually did shoot this fsn_mark. That's fine too * since multiple calls to destroy_mark is perfectly safe, if * we found a dn_mark already attached to the inode, just sod * off silently as the flush at close time dealt with it. */ if (dn_mark == new_dn_mark) destroy = 1; goto out; } __f_setown(filp, task_pid(current), PIDTYPE_PID, 0); error = attach_dn(dn, dn_mark, id, fd, filp, mask); /* !error means that we attached the dn to the dn_mark, so don't free it */ if (!error) dn = NULL; /* -EEXIST means that we didn't add this new dn and used an old one. * that isn't an error (and the unused dn should be freed) */ else if (error == -EEXIST) error = 0; dnotify_recalc_inode_mask(fsn_mark); out: spin_unlock(&fsn_mark->lock); if (destroy) fsnotify_detach_mark(fsn_mark); mutex_unlock(&dnotify_group->mark_mutex); if (destroy) fsnotify_free_mark(fsn_mark); fsnotify_put_mark(fsn_mark); out_err: if (new_fsn_mark) fsnotify_put_mark(new_fsn_mark); if (dn) kmem_cache_free(dnotify_struct_cache, dn); return error; }


eric pariseric paris28459.79%526.32%
andrew mortonandrew morton255.26%315.79%
stephen rothwellstephen rothwell234.84%210.53%
al viroal viro122.53%210.53%
jan karajan kara102.11%15.26%
lino sanfilippolino sanfilippo81.68%15.26%
stephen d. smalleystephen d. smalley51.05%15.26%
james morrisjames morris51.05%15.26%
eric w. biedermaneric w. biederman10.21%15.26%
christoph lameterchristoph lameter10.21%15.26%

static int __init dnotify_init(void) { dnotify_struct_cache = KMEM_CACHE(dnotify_struct, SLAB_PANIC); dnotify_mark_cache = KMEM_CACHE(dnotify_mark, SLAB_PANIC); dnotify_group = fsnotify_alloc_group(&dnotify_fsnotify_ops); if (IS_ERR(dnotify_group)) panic("unable to allocate fsnotify group for dnotify\n"); return 0; }


eric pariseric paris3162.00%375.00%


Overall Contributors

eric pariseric paris99168.72%928.12%
stephen rothwellstephen rothwell956.59%26.25%
jan karajan kara674.65%412.50%
andrew mortonandrew morton292.01%39.38%
al viroal viro191.32%412.50%
lino sanfilippolino sanfilippo151.04%13.12%
andreas gruenbacherandreas gruenbacher90.62%13.12%
james morrisjames morris50.35%13.12%
stephen d. smalleystephen d. smalley50.35%13.12%
christoph lameterchristoph lameter30.21%26.25%
arnaldo carvalho de meloarnaldo carvalho de melo30.21%13.12%
eric dumazeteric dumazet20.14%13.12%
eric w. biedermaneric w. biederman10.07%13.12%
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