From 621e155a3591962420eacdd39f6f0aa29ceb221e Mon Sep 17 00:00:00 2001 From: Nick Piggin Date: Fri, 7 Jan 2011 17:49:27 +1100 Subject: fs: change d_compare for rcu-walk Change d_compare so it may be called from lock-free RCU lookups. This does put significant restrictions on what may be done from the callback, however there don't seem to have been any problems with in-tree fses. If some strange use case pops up that _really_ cannot cope with the rcu-walk rules, we can just add new rcu-unaware callbacks, which would cause name lookup to drop out of rcu-walk mode. For in-tree filesystems, this is just a mechanical change. Signed-off-by: Nick Piggin --- fs/fat/namei_msdos.c | 14 ++++++++------ fs/fat/namei_vfat.c | 33 ++++++++++++++++++++------------- 2 files changed, 28 insertions(+), 19 deletions(-) (limited to 'fs/fat') diff --git a/fs/fat/namei_msdos.c b/fs/fat/namei_msdos.c index 3345aabd1dd7..99d3c7ac973c 100644 --- a/fs/fat/namei_msdos.c +++ b/fs/fat/namei_msdos.c @@ -164,16 +164,18 @@ static int msdos_hash(struct dentry *dentry, struct qstr *qstr) * Compare two msdos names. If either of the names are invalid, * we fall back to doing the standard name comparison. */ -static int msdos_cmp(struct dentry *dentry, struct qstr *a, struct qstr *b) +static int msdos_cmp(const struct dentry *parent, const struct inode *pinode, + const struct dentry *dentry, const struct inode *inode, + unsigned int len, const char *str, const struct qstr *name) { - struct fat_mount_options *options = &MSDOS_SB(dentry->d_sb)->options; + struct fat_mount_options *options = &MSDOS_SB(parent->d_sb)->options; unsigned char a_msdos_name[MSDOS_NAME], b_msdos_name[MSDOS_NAME]; int error; - error = msdos_format_name(a->name, a->len, a_msdos_name, options); + error = msdos_format_name(name->name, name->len, a_msdos_name, options); if (error) goto old_compare; - error = msdos_format_name(b->name, b->len, b_msdos_name, options); + error = msdos_format_name(str, len, b_msdos_name, options); if (error) goto old_compare; error = memcmp(a_msdos_name, b_msdos_name, MSDOS_NAME); @@ -182,8 +184,8 @@ out: old_compare: error = 1; - if (a->len == b->len) - error = memcmp(a->name, b->name, a->len); + if (name->len == len) + error = memcmp(name->name, str, len); goto out; } diff --git a/fs/fat/namei_vfat.c b/fs/fat/namei_vfat.c index b936703b8924..95e00ab84c3f 100644 --- a/fs/fat/namei_vfat.c +++ b/fs/fat/namei_vfat.c @@ -85,15 +85,18 @@ static int vfat_revalidate_ci(struct dentry *dentry, struct nameidata *nd) } /* returns the length of a struct qstr, ignoring trailing dots */ -static unsigned int vfat_striptail_len(struct qstr *qstr) +static unsigned int __vfat_striptail_len(unsigned int len, const char *name) { - unsigned int len = qstr->len; - - while (len && qstr->name[len - 1] == '.') + while (len && name[len - 1] == '.') len--; return len; } +static unsigned int vfat_striptail_len(const struct qstr *qstr) +{ + return __vfat_striptail_len(qstr->len, qstr->name); +} + /* * Compute the hash for the vfat name corresponding to the dentry. * Note: if the name is invalid, we leave the hash code unchanged so @@ -133,16 +136,18 @@ static int vfat_hashi(struct dentry *dentry, struct qstr *qstr) /* * Case insensitive compare of two vfat names. */ -static int vfat_cmpi(struct dentry *dentry, struct qstr *a, struct qstr *b) +static int vfat_cmpi(const struct dentry *parent, const struct inode *pinode, + const struct dentry *dentry, const struct inode *inode, + unsigned int len, const char *str, const struct qstr *name) { - struct nls_table *t = MSDOS_SB(dentry->d_inode->i_sb)->nls_io; + struct nls_table *t = MSDOS_SB(parent->d_sb)->nls_io; unsigned int alen, blen; /* A filename cannot end in '.' or we treat it like it has none */ - alen = vfat_striptail_len(a); - blen = vfat_striptail_len(b); + alen = vfat_striptail_len(name); + blen = __vfat_striptail_len(len, str); if (alen == blen) { - if (nls_strnicmp(t, a->name, b->name, alen) == 0) + if (nls_strnicmp(t, name->name, str, alen) == 0) return 0; } return 1; @@ -151,15 +156,17 @@ static int vfat_cmpi(struct dentry *dentry, struct qstr *a, struct qstr *b) /* * Case sensitive compare of two vfat names. */ -static int vfat_cmp(struct dentry *dentry, struct qstr *a, struct qstr *b) +static int vfat_cmp(const struct dentry *parent, const struct inode *pinode, + const struct dentry *dentry, const struct inode *inode, + unsigned int len, const char *str, const struct qstr *name) { unsigned int alen, blen; /* A filename cannot end in '.' or we treat it like it has none */ - alen = vfat_striptail_len(a); - blen = vfat_striptail_len(b); + alen = vfat_striptail_len(name); + blen = __vfat_striptail_len(len, str); if (alen == blen) { - if (strncmp(a->name, b->name, alen) == 0) + if (strncmp(name->name, str, alen) == 0) return 0; } return 1; -- cgit v1.2.3