summaryrefslogtreecommitdiffstats
path: root/fs/overlayfs/inode.c
diff options
context:
space:
mode:
Diffstat (limited to 'fs/overlayfs/inode.c')
-rw-r--r--fs/overlayfs/inode.c66
1 files changed, 38 insertions, 28 deletions
diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c
index b045cf1826fc..79e8994e3bc1 100644
--- a/fs/overlayfs/inode.c
+++ b/fs/overlayfs/inode.c
@@ -75,10 +75,9 @@ out:
return err;
}
-static int ovl_map_dev_ino(struct dentry *dentry, struct kstat *stat,
- struct ovl_layer *lower_layer)
+static int ovl_map_dev_ino(struct dentry *dentry, struct kstat *stat, int fsid)
{
- bool samefs = ovl_same_sb(dentry->d_sb);
+ bool samefs = ovl_same_fs(dentry->d_sb);
unsigned int xinobits = ovl_xino_bits(dentry->d_sb);
if (samefs) {
@@ -100,12 +99,10 @@ static int ovl_map_dev_ino(struct dentry *dentry, struct kstat *stat,
* persistent for a given layer configuration.
*/
if (stat->ino >> shift) {
- pr_warn_ratelimited("overlayfs: inode number too big (%pd2, ino=%llu, xinobits=%d)\n",
+ pr_warn_ratelimited("inode number too big (%pd2, ino=%llu, xinobits=%d)\n",
dentry, stat->ino, xinobits);
} else {
- if (lower_layer)
- stat->ino |= ((u64)lower_layer->fsid) << shift;
-
+ stat->ino |= ((u64)fsid) << shift;
stat->dev = dentry->d_sb->s_dev;
return 0;
}
@@ -124,15 +121,14 @@ static int ovl_map_dev_ino(struct dentry *dentry, struct kstat *stat,
*/
stat->dev = dentry->d_sb->s_dev;
stat->ino = dentry->d_inode->i_ino;
- } else if (lower_layer && lower_layer->fsid) {
+ } else {
/*
* For non-samefs setup, if we cannot map all layers st_ino
* to a unified address space, we need to make sure that st_dev
- * is unique per lower fs. Upper layer uses real st_dev and
- * lower layers use the unique anonymous bdev assigned to the
- * lower fs.
+ * is unique per underlying fs, so we use the unique anonymous
+ * bdev assigned to the underlying fs.
*/
- stat->dev = lower_layer->fs->pseudo_dev;
+ stat->dev = OVL_FS(dentry->d_sb)->fs[fsid].pseudo_dev;
}
return 0;
@@ -146,8 +142,7 @@ int ovl_getattr(const struct path *path, struct kstat *stat,
struct path realpath;
const struct cred *old_cred;
bool is_dir = S_ISDIR(dentry->d_inode->i_mode);
- bool samefs = ovl_same_sb(dentry->d_sb);
- struct ovl_layer *lower_layer = NULL;
+ int fsid = 0;
int err;
bool metacopy_blocks = false;
@@ -168,9 +163,9 @@ int ovl_getattr(const struct path *path, struct kstat *stat,
* If lower filesystem supports NFS file handles, this also guaranties
* persistent st_ino across mount cycle.
*/
- if (!is_dir || samefs || ovl_xino_bits(dentry->d_sb)) {
+ if (!is_dir || ovl_same_dev(dentry->d_sb)) {
if (!OVL_TYPE_UPPER(type)) {
- lower_layer = ovl_layer_lower(dentry);
+ fsid = ovl_layer_lower(dentry)->fsid;
} else if (OVL_TYPE_ORIGIN(type)) {
struct kstat lowerstat;
u32 lowermask = STATX_INO | STATX_BLOCKS |
@@ -200,14 +195,8 @@ int ovl_getattr(const struct path *path, struct kstat *stat,
if (ovl_test_flag(OVL_INDEX, d_inode(dentry)) ||
(!ovl_verify_lower(dentry->d_sb) &&
(is_dir || lowerstat.nlink == 1))) {
- lower_layer = ovl_layer_lower(dentry);
- /*
- * Cannot use origin st_dev;st_ino because
- * origin inode content may differ from overlay
- * inode content.
- */
- if (samefs || lower_layer->fsid)
- stat->ino = lowerstat.ino;
+ fsid = ovl_layer_lower(dentry)->fsid;
+ stat->ino = lowerstat.ino;
}
/*
@@ -241,7 +230,7 @@ int ovl_getattr(const struct path *path, struct kstat *stat,
}
}
- err = ovl_map_dev_ino(dentry, stat, lower_layer);
+ err = ovl_map_dev_ino(dentry, stat, fsid);
if (err)
goto out;
@@ -527,6 +516,27 @@ static const struct address_space_operations ovl_aops = {
* [...] &ovl_i_mutex_dir_key[depth] (stack_depth=2)
* [...] &ovl_i_mutex_dir_key[depth]#2 (stack_depth=1)
* [...] &type->i_mutex_dir_key (stack_depth=0)
+ *
+ * Locking order w.r.t ovl_want_write() is important for nested overlayfs.
+ *
+ * This chain is valid:
+ * - inode->i_rwsem (inode_lock[2])
+ * - upper_mnt->mnt_sb->s_writers (ovl_want_write[0])
+ * - OVL_I(inode)->lock (ovl_inode_lock[2])
+ * - OVL_I(lowerinode)->lock (ovl_inode_lock[1])
+ *
+ * And this chain is valid:
+ * - inode->i_rwsem (inode_lock[2])
+ * - OVL_I(inode)->lock (ovl_inode_lock[2])
+ * - lowerinode->i_rwsem (inode_lock[1])
+ * - OVL_I(lowerinode)->lock (ovl_inode_lock[1])
+ *
+ * But lowerinode->i_rwsem SHOULD NOT be acquired while ovl_want_write() is
+ * held, because it is in reverse order of the non-nested case using the same
+ * upper fs:
+ * - inode->i_rwsem (inode_lock[1])
+ * - upper_mnt->mnt_sb->s_writers (ovl_want_write[0])
+ * - OVL_I(inode)->lock (ovl_inode_lock[1])
*/
#define OVL_MAX_NESTING FILESYSTEM_MAX_STACK_DEPTH
@@ -565,7 +575,7 @@ static void ovl_fill_inode(struct inode *inode, umode_t mode, dev_t rdev,
* ovl_new_inode(), ino arg is 0, so i_ino will be updated to real
* upper inode i_ino on ovl_inode_init() or ovl_inode_update().
*/
- if (ovl_same_sb(inode->i_sb) || xinobits) {
+ if (ovl_same_dev(inode->i_sb)) {
inode->i_ino = ino;
if (xinobits && fsid && !(ino >> (64 - xinobits)))
inode->i_ino |= (unsigned long)fsid << (64 - xinobits);
@@ -698,7 +708,7 @@ unsigned int ovl_get_nlink(struct dentry *lowerdentry,
return nlink;
fail:
- pr_warn_ratelimited("overlayfs: failed to get index nlink (%pd2, err=%i)\n",
+ pr_warn_ratelimited("failed to get index nlink (%pd2, err=%i)\n",
upperdentry, err);
return fallback;
}
@@ -969,7 +979,7 @@ out:
return inode;
out_err:
- pr_warn_ratelimited("overlayfs: failed to get inode (%i)\n", err);
+ pr_warn_ratelimited("failed to get inode (%i)\n", err);
inode = ERR_PTR(err);
goto out;
}
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-26 23:27:02 +0100