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Date: Wed, 12 Jun 2024 17:09:55 +1000 Message-id: <171817619547.14261.975798725161704336@noble.neil.brown.name> X-Spamd-Result: default: False [-4.51 / 50.00]; BAYES_HAM(-3.00)[100.00%]; NEURAL_HAM_LONG(-1.00)[-1.000]; R_DKIM_ALLOW(-0.20)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; MX_GOOD(-0.01)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; FREEMAIL_ENVRCPT(0.00)[gmail.com]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; ARC_NA(0.00)[]; FUZZY_BLOCKED(0.00)[rspamd.com]; MIME_TRACE(0.00)[0:+]; FREEMAIL_CC(0.00)[gmail.com,arm.com,lists.linux.it,vger.kernel.org]; DKIM_TRACE(0.00)[suse.de:+]; TO_DN_SOME(0.00)[]; RCVD_COUNT_TWO(0.00)[2]; FROM_EQ_ENVFROM(0.00)[]; FROM_HAS_DN(0.00)[]; RCVD_TLS_ALL(0.00)[]; DWL_DNSWL_BLOCKED(0.00)[suse.de:dkim]; RCVD_VIA_SMTP_AUTH(0.00)[]; RCPT_COUNT_SEVEN(0.00)[9]; MISSING_XM_UA(0.00)[]; DBL_BLOCKED_OPENRESOLVER(0.00)[suse.de:email,suse.de:dkim] X-Rspamd-Action: no action X-Rspamd-Server: rspamd2.dmz-prg2.suse.org X-Rspamd-Queue-Id: CE1ED5BD04 X-Spam-Flag: NO X-Spam-Score: -4.51 X-Spam-Level: When a file is opened and created with open(..., O_CREAT) we get both the CREATE and OPEN fsnotify events and would expect them in that order. For most filesystems we get them in that order because open_last_lookups() calls fsnofify_create() and then do_open() (from path_openat()) calls vfs_open()->do_dentry_open() which calls fsnotify_open(). However when ->atomic_open is used, the do_dentry_open() -> fsnotify_open() call happens from finish_open() which is called from the ->atomic_open handler in lookup_open() which is called *before* open_last_lookups() calls fsnotify_create. So we get the "open" notification before "create" - which is backwards. ltp testcase inotify02 tests this and reports the inconsistency. This patch lifts the fsnotify_open() call out of do_dentry_open() and places it higher up the call stack. There are three callers of do_dentry_open(). For vfs_open() and kernel_file_open() the fsnotify_open() is placed directly in that caller so there should be no behavioural change. For finish_open() there are two cases: - finish_open is used in ->atomic_open handlers. For these we add a call to fsnotify_open() at the top of do_open() if FMODE_OPENED is set - which means do_dentry_open() has been called. - finish_open is used in ->tmpfile() handlers. For these a similar call to fsnotify_open() is added to vfs_tmpfile() With this patch NFSv3 is restored to its previous behaviour (before ->atomic_open support was added) of generating CREATE notifications before OPEN, and NFSv4 now has that same correct ordering that is has not had before. I haven't tested other filesystems. Fixes: 7c6c5249f061 ("NFS: add atomic_open for NFSv3 to handle O_TRUNC correctly.") Reported-by: James Clark Closes: https://lore.kernel.org/all/01c3bf2e-eb1f-4b7f-a54f-d2a05dd3d8c8@arm.com Signed-off-by: NeilBrown Tested-by: James Clark --- fs/namei.c | 5 +++++ fs/open.c | 19 ++++++++++++------- 2 files changed, 17 insertions(+), 7 deletions(-) diff --git a/fs/namei.c b/fs/namei.c index 37fb0a8aa09a..057afacc4b60 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -3612,6 +3612,9 @@ static int do_open(struct nameidata *nd, int acc_mode; int error; + if (file->f_mode & FMODE_OPENED) + fsnotify_open(file); + if (!(file->f_mode & (FMODE_OPENED | FMODE_CREATED))) { error = complete_walk(nd); if (error) @@ -3700,6 +3703,8 @@ int vfs_tmpfile(struct mnt_idmap *idmap, mode = vfs_prepare_mode(idmap, dir, mode, mode, mode); error = dir->i_op->tmpfile(idmap, dir, file, mode); dput(child); + if (file->f_mode & FMODE_OPENED) + fsnotify_open(file); if (error) return error; /* Don't check for other permissions, the inode was just created */ diff --git a/fs/open.c b/fs/open.c index 89cafb572061..970f299c0e77 100644 --- a/fs/open.c +++ b/fs/open.c @@ -1004,11 +1004,6 @@ static int do_dentry_open(struct file *f, } } - /* - * Once we return a file with FMODE_OPENED, __fput() will call - * fsnotify_close(), so we need fsnotify_open() here for symmetry. - */ - fsnotify_open(f); return 0; cleanup_all: @@ -1085,8 +1080,17 @@ EXPORT_SYMBOL(file_path); */ int vfs_open(const struct path *path, struct file *file) { + int ret; + file->f_path = *path; - return do_dentry_open(file, NULL); + ret = do_dentry_open(file, NULL); + if (!ret) + /* + * Once we return a file with FMODE_OPENED, __fput() will call + * fsnotify_close(), so we need fsnotify_open() here for symmetry. + */ + fsnotify_open(file); + return ret; } struct file *dentry_open(const struct path *path, int flags, @@ -1178,7 +1182,8 @@ struct file *kernel_file_open(const struct path *path, int flags, if (error) { fput(f); f = ERR_PTR(error); - } + } else + fsnotify_open(f); return f; } EXPORT_SYMBOL_GPL(kernel_file_open);