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vfs: generate FS_CREATE before FS_OPEN when ->atomic_open used.
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 open_last_lookups() 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: 7c6c524 ("NFS: add atomic_open for NFSv3 to handle O_TRUNC correctly.") Reported-by: James Clark <[email protected]> Closes: https://lore.kernel.org/all/[email protected] Signed-off-by: NeilBrown <[email protected]> Link: https://lore.kernel.org/r/[email protected] Fixes: 7b8c9d7 ("fsnotify: move fsnotify_open() hook into do_dentry_open()") Tested-by: James Clark <[email protected]> Signed-off-by: Jan Kara <[email protected]> Link: https://lore.kernel.org/r/[email protected] Reviewed-by: Amir Goldstein <[email protected]> Signed-off-by: Christian Brauner <[email protected]>
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