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| author | Miklos Szeredi <mszeredi@redhat.com> | 2016-09-01 11:11:59 +0200 |
|---|---|---|
| committer | Miklos Szeredi <mszeredi@redhat.com> | 2016-09-01 11:11:59 +0200 |
| commit | 2a3a2a3f35249412e35fbb48b743348c40373409 (patch) | |
| tree | 4615559df3c1faddf9ef388adce449fb8e89f680 /fs/overlayfs | |
| parent | 5201dc449e4b6b6d7e92f7f974269b11681f98b5 (diff) | |
| download | linux-2a3a2a3f35249412e35fbb48b743348c40373409.tar.gz linux-2a3a2a3f35249412e35fbb48b743348c40373409.tar.bz2 linux-2a3a2a3f35249412e35fbb48b743348c40373409.zip | |
ovl: don't cache acl on overlay layer
Some operations (setxattr/chmod) can make the cached acl stale. We either
need to clear overlay's acl cache for the affected inode or prevent acl
caching on the overlay altogether. Preventing caching has the following
advantages:
- no double caching, less memory used
- overlay cache doesn't go stale when fs clears it's own cache
Possible disadvantage is performance loss. If that becomes a problem
get_acl() can be optimized for overlayfs.
This patch disables caching by pre setting i_*acl to a value that
- has bit 0 set, so is_uncached_acl() will return true
- is not equal to ACL_NOT_CACHED, so get_acl() will not overwrite it
The constant -3 was chosen for this purpose.
Fixes: 39a25b2b3762 ("ovl: define ->get_acl() for overlay inodes")
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Diffstat (limited to 'fs/overlayfs')
| -rw-r--r-- | fs/overlayfs/inode.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c index d50d1ead1b6f..47a4f33df47b 100644 --- a/fs/overlayfs/inode.c +++ b/fs/overlayfs/inode.c @@ -416,6 +416,9 @@ static void ovl_fill_inode(struct inode *inode, umode_t mode) inode->i_ino = get_next_ino(); inode->i_mode = mode; inode->i_flags |= S_NOCMTIME; +#ifdef CONFIG_FS_POSIX_ACL + inode->i_acl = inode->i_default_acl = ACL_DONT_CACHE; +#endif mode &= S_IFMT; switch (mode) { |