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| author | Dean Deng <deandeng@google.com> | 2020-08-24 11:28:28 -0700 |
|---|---|---|
| committer | Andrei Vagin <avagin@gmail.com> | 2020-09-09 17:53:10 -0700 |
| commit | 78c8c9e4c8a47818df14aac192a33a0f7b9f9006 (patch) | |
| tree | 2f76a6540b90710b84c6275c06fbb85b21ad79a3 /pkg/sentry/vfs | |
| parent | 194bcb6ca3c3a6ef59a471b5d46886b41575d1bc (diff) | |
Update inotify documentation for gofer filesystem.
We now allow hard links to be created within gofer fs (see
github.com/google/gvisor/commit/f20e63e31b56784c596897e86f03441f9d05f567).
Update the inotify documentation accordingly.
PiperOrigin-RevId: 328177485
Diffstat (limited to 'pkg/sentry/vfs')
| -rw-r--r-- | pkg/sentry/vfs/g3doc/inotify.md | 18 |
1 files changed, 9 insertions, 9 deletions
diff --git a/pkg/sentry/vfs/g3doc/inotify.md b/pkg/sentry/vfs/g3doc/inotify.md index e7da49faa..833db213f 100644 --- a/pkg/sentry/vfs/g3doc/inotify.md +++ b/pkg/sentry/vfs/g3doc/inotify.md @@ -28,9 +28,9 @@ The set of all watches held on a single file (i.e., the watch target) is stored in vfs.Watches. Each watch will belong to a different inotify instance (an instance can only have one watch on any watch target). The watches are stored in a map indexed by their vfs.Inotify owner’s id. Hard links and file descriptions -to a single file will all share the same vfs.Watches. Activity on the target -causes its vfs.Watches to generate notifications on its watches’ inotify -instances. +to a single file will all share the same vfs.Watches (with the exception of the +gofer filesystem, described in a later section). Activity on the target causes +its vfs.Watches to generate notifications on its watches’ inotify instances. ### vfs.Watch @@ -103,12 +103,12 @@ inotify: unopened p9 file (and possibly an open FID), through which the Sentry interacts with the gofer. * *Solution:* Because there is no inode structure stored in the sandbox, - inotify watches must be held on the dentry. This would be an issue in - the presence of hard links, where multiple dentries would need to share - the same set of watches, but in VFS2, we do not support the internal - creation of hard links on gofer fs. As a result, we make the assumption - that every dentry corresponds to a unique inode. However, the next point - raises an issue with this assumption: + inotify watches must be held on the dentry. For the purposes of inotify, + we assume that every dentry corresponds to a unique inode, which may + cause unexpected behavior in the presence of hard links, where multiple + dentries should share the same set of watches. Indeed, it is impossible + for us to be absolutely sure whether dentries correspond to the same + file or not, due to the following point: * **The Sentry cannot always be aware of hard links on the remote filesystem.** There is no way for us to confirm whether two files on the remote filesystem are actually links to the same inode. QIDs and inodes are |