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ANDROID: sdcardfs: Add option to drop unused dentries

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This adds the nocache mount option, which will cause sdcardfs to always
drop dentries that are not in use, preventing cached entries from
holding on to lower dentries, which could  cause strange behavior when
bypassing the sdcardfs layer and directly changing the lower fs.

Change-Id: I70268584a20b989ae8cfdd278a2e4fa1605217fb
Signed-off-by: Daniel Rosenberg <drosen@google.com>
This commit is contained in:
Daniel Rosenberg 2018-07-06 16:24:27 -07:00
parent 3411c22ecc
commit 1bdb20fcd4
4 changed files with 16 additions and 0 deletions
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7
fs/sdcardfs/dentry.c
View file

@ -123,6 +123,12 @@ out:
return err;
}
/* 1 = delete, 0 = cache */
static int sdcardfs_d_delete(const struct dentry *d)
{
return SDCARDFS_SB(d->d_sb)->options.nocache ? 1 : 0;
}
static void sdcardfs_d_release(struct dentry *dentry)
{
if (!dentry || !dentry->d_fsdata)
@ -182,6 +188,7 @@ static void sdcardfs_canonical_path(const struct path *path,
const struct dentry_operations sdcardfs_ci_dops = {
.d_revalidate = sdcardfs_d_revalidate,
.d_delete = sdcardfs_d_delete,
.d_release = sdcardfs_d_release,
.d_hash = sdcardfs_hash_ci,
.d_compare = sdcardfs_cmp_ci,

6
fs/sdcardfs/main.c
View file

@ -34,6 +34,7 @@ enum {
Opt_reserved_mb,
Opt_gid_derivation,
Opt_default_normal,
Opt_nocache,
Opt_err,
};
@ -48,6 +49,7 @@ static const match_table_t sdcardfs_tokens = {
{Opt_gid_derivation, "derive_gid"},
{Opt_default_normal, "default_normal"},
{Opt_reserved_mb, "reserved_mb=%u"},
{Opt_nocache, "nocache"},
{Opt_err, NULL}
};
@ -71,6 +73,7 @@ static int parse_options(struct super_block *sb, char *options, int silent,
/* by default, gid derivation is off */
opts->gid_derivation = false;
opts->default_normal = false;
opts->nocache = false;
*debug = 0;
@ -128,6 +131,9 @@ static int parse_options(struct super_block *sb, char *options, int silent,
case Opt_default_normal:
opts->default_normal = true;
break;
case Opt_nocache:
opts->nocache = true;
break;
/* unknown option */
default:
if (!silent)

1
fs/sdcardfs/sdcardfs.h
View file

@ -198,6 +198,7 @@ struct sdcardfs_mount_options {
bool gid_derivation;
bool default_normal;
unsigned int reserved_mb;
bool nocache;
};
struct sdcardfs_vfsmount_options {

2
fs/sdcardfs/super.c
View file

@ -311,6 +311,8 @@ static int sdcardfs_show_options(struct vfsmount *mnt, struct seq_file *m,
seq_puts(m, ",default_normal");
if (opts->reserved_mb != 0)
seq_printf(m, ",reserved=%uMB", opts->reserved_mb);
if (opts->nocache)
seq_printf(m, ",nocache");
return 0;
};