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ovl: remove unused code in lowerdir param parsing

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Commit beae836e9c ("ovl: temporarily disable appending lowedirs")
removed the ability to append lowerdirs with syntax lowerdir=":<path>".
Remove leftover code and comments that are irrelevant with lowerdir
append mode disabled.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
This commit is contained in:
Amir Goldstein 2023-10-28 12:07:45 +03:00
parent bb7055a734
commit c835110b58
1 changed files with 16 additions and 79 deletions
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95
fs/overlayfs/params.c
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@ -346,7 +346,7 @@ static void ovl_parse_param_drop_lowerdir(struct ovl_fs_context *ctx)
/*
* Parse lowerdir= mount option:
*
* (1) lowerdir=/lower1:/lower2:/lower3::/data1::/data2
* e.g.: lowerdir=/lower1:/lower2:/lower3::/data1::/data2
* Set "/lower1", "/lower2", and "/lower3" as lower layers and
* "/data1" and "/data2" as data lower layers. Any existing lower
* layers are replaced.
@ -356,9 +356,9 @@ static int ovl_parse_param_lowerdir(const char *name, struct fs_context *fc)
int err;
struct ovl_fs_context *ctx = fc->fs_private;
struct ovl_fs_context_layer *l;
char *dup = NULL, *dup_iter;
char *dup = NULL, *iter;
ssize_t nr_lower = 0, nr = 0, nr_data = 0;
bool append = false, data_layer = false;
bool data_layer = false;
/*
* Ensure we're backwards compatible with mount(2)
@ -366,10 +366,10 @@ static int ovl_parse_param_lowerdir(const char *name, struct fs_context *fc)
*/
/* drop all existing lower layers */
if (!*name) {
ovl_parse_param_drop_lowerdir(ctx);
ovl_parse_param_drop_lowerdir(ctx);
if (!*name)
return 0;
}
if (*name == ':') {
pr_err("cannot append lower layer");
@ -385,36 +385,11 @@ static int ovl_parse_param_lowerdir(const char *name, struct fs_context *fc)
if (nr_lower < 0)
goto out_err;
if ((nr_lower > OVL_MAX_STACK) ||
(append && (size_add(ctx->nr, nr_lower) > OVL_MAX_STACK))) {
if (nr_lower > OVL_MAX_STACK) {
pr_err("too many lower directories, limit is %d\n", OVL_MAX_STACK);
goto out_err;
}
if (!append)
ovl_parse_param_drop_lowerdir(ctx);
/*
* (1) append
*
* We want nr <= nr_lower <= capacity We know nr > 0 and nr <=
* capacity. If nr == 0 this wouldn't be append. If nr +
* nr_lower is <= capacity then nr <= nr_lower <= capacity
* already holds. If nr + nr_lower exceeds capacity, we realloc.
*
* (2) replace
*
* Ensure we're backwards compatible with mount(2) which allows
* "lowerdir=/a:/b:/c,lowerdir=/d:/e:/f" causing the last
* specified lowerdir mount option to win.
*
* We want nr <= nr_lower <= capacity We know either (i) nr == 0
* or (ii) nr > 0. We also know nr_lower > 0. The capacity
* could've been changed multiple times already so we only know
* nr <= capacity. If nr + nr_lower > capacity we realloc,
* otherwise nr <= nr_lower <= capacity holds already.
*/
nr_lower += ctx->nr;
if (nr_lower > ctx->capacity) {
err = -ENOMEM;
l = krealloc_array(ctx->lower, nr_lower, sizeof(*ctx->lower),
@ -426,41 +401,17 @@ static int ovl_parse_param_lowerdir(const char *name, struct fs_context *fc)
ctx->capacity = nr_lower;
}
/*
* (3) By (1) and (2) we know nr <= nr_lower <= capacity.
* (4) If ctx->nr == 0 => replace
* We have verified above that the lowerdir mount option
* isn't an append, i.e., the lowerdir mount option
* doesn't start with ":" or "::".
* (4.1) The lowerdir mount options only contains regular lower
* layers ":".
* => Nothing to verify.
* (4.2) The lowerdir mount options contains regular ":" and
* data "::" layers.
* => We need to verify that data lower layers "::" aren't
* followed by regular ":" lower layers
* (5) If ctx->nr > 0 => append
* We know that there's at least one regular layer
* otherwise we would've failed when parsing the previous
* lowerdir mount option.
* (5.1) The lowerdir mount option is a regular layer ":" append
* => We need to verify that no data layers have been
* specified before.
* (5.2) The lowerdir mount option is a data layer "::" append
* We know that there's at least one regular layer or
* other data layers. => There's nothing to verify.
*/
dup_iter = dup;
for (nr = ctx->nr; nr < nr_lower; nr++) {
l = &ctx->lower[nr];
iter = dup;
l = ctx->lower;
for (nr = 0; nr < nr_lower; nr++, l++) {
memset(l, 0, sizeof(*l));
err = ovl_mount_dir(dup_iter, &l->path, false);
err = ovl_mount_dir(iter, &l->path, false);
if (err)
goto out_put;
err = -ENOMEM;
l->name = kstrdup(dup_iter, GFP_KERNEL_ACCOUNT);
l->name = kstrdup(iter, GFP_KERNEL_ACCOUNT);
if (!l->name)
goto out_put;
@ -472,8 +423,8 @@ static int ovl_parse_param_lowerdir(const char *name, struct fs_context *fc)
break;
err = -EINVAL;
dup_iter = strchr(dup_iter, '\0') + 1;
if (*dup_iter) {
iter = strchr(iter, '\0') + 1;
if (*iter) {
/*
* This is a regular layer so we require that
* there are no data layers.
@ -489,7 +440,7 @@ static int ovl_parse_param_lowerdir(const char *name, struct fs_context *fc)
/* This is a data lower layer. */
data_layer = true;
dup_iter++;
iter++;
}
ctx->nr = nr_lower;
ctx->nr_data += nr_data;
@ -497,21 +448,7 @@ static int ovl_parse_param_lowerdir(const char *name, struct fs_context *fc)
return 0;
out_put:
/*
* We know nr >= ctx->nr < nr_lower. If we failed somewhere
* we want to undo until nr == ctx->nr. This is correct for
* both ctx->nr == 0 and ctx->nr > 0.
*/
for (; nr >= ctx->nr; nr--) {
l = &ctx->lower[nr];
kfree(l->name);
l->name = NULL;
path_put(&l->path);
/* don't overflow */
if (nr == 0)
break;
}
ovl_parse_param_drop_lowerdir(ctx);
out_err:
kfree(dup);