From 675c187cc41a91dad988fc43434ea63d4370c2de Mon Sep 17 00:00:00 2001 From: Conrad Meyer Date: Thu, 19 Jan 2017 16:46:05 +0000 Subject: [PATCH] ffs_vnops: Simplify extattr access As suggested in r167010, use the structure type and macros to access and modify UFS2 extended attributes. Add assertions that pointers are aligned in places where we now access the data through a structure pointer, instead of character-by-character. PR: 216127 Reported by: dewayne at heuristicsystems.com.au Reviewed by: kib@ Sponsored by: Dell EMC Isilon Differential Revision: https://reviews.freebsd.org/D9225 --- sys/ufs/ffs/ffs_vnops.c | 190 ++++++++++++++++++---------------------- 1 file changed, 85 insertions(+), 105 deletions(-) diff --git a/sys/ufs/ffs/ffs_vnops.c b/sys/ufs/ffs/ffs_vnops.c index f5a45f1c1787..0b5c61765d7a 100644 --- a/sys/ufs/ffs/ffs_vnops.c +++ b/sys/ufs/ffs/ffs_vnops.c @@ -100,6 +100,9 @@ __FBSDID("$FreeBSD$"); #include "opt_directio.h" #include "opt_ffs.h" +#define ALIGNED_TO(ptr, s) \ + (((uintptr_t)(ptr) & (_Alignof(s) - 1)) == 0) + #ifdef DIRECTIO extern int ffs_rawread(struct vnode *vp, struct uio *uio, int *workdone); #endif @@ -1100,46 +1103,30 @@ ffs_extwrite(struct vnode *vp, struct uio *uio, int ioflag, struct ucred *ucred) * the length of the EA, and possibly the pointer to the entry and to the data. */ static int -ffs_findextattr(u_char *ptr, u_int length, int nspace, const char *name, u_char **eap, u_char **eac) +ffs_findextattr(u_char *ptr, u_int length, int nspace, const char *name, + struct extattr **eapp, u_char **eac) { - u_char *p, *pe, *pn, *p0; - int eapad1, eapad2, ealength, ealen, nlen; - uint32_t ul; + struct extattr *eap, *eaend; + size_t nlen; - pe = ptr + length; nlen = strlen(name); - - for (p = ptr; p < pe; p = pn) { - p0 = p; - bcopy(p, &ul, sizeof(ul)); - pn = p + ul; + KASSERT(ALIGNED_TO(ptr, struct extattr), ("unaligned")); + eap = (struct extattr *)ptr; + eaend = (struct extattr *)(ptr + length); + for (; eap < eaend; eap = EXTATTR_NEXT(eap)) { /* make sure this entry is complete */ - if (pn > pe) + if (EXTATTR_NEXT(eap) > eaend) break; - p += sizeof(uint32_t); - if (*p != nspace) + if (eap->ea_namespace != nspace || eap->ea_namelength != nlen + || memcmp(eap->ea_name, name, nlen) != 0) continue; - p++; - eapad2 = *p++; - if (*p != nlen) - continue; - p++; - if (bcmp(p, name, nlen)) - continue; - ealength = sizeof(uint32_t) + 3 + nlen; - eapad1 = 8 - (ealength % 8); - if (eapad1 == 8) - eapad1 = 0; - ealength += eapad1; - ealen = ul - ealength - eapad2; - p += nlen + eapad1; - if (eap != NULL) - *eap = p0; + if (eapp != NULL) + *eapp = eap; if (eac != NULL) - *eac = p; - return (ealen); + *eac = EXTATTR_CONTENT(eap); + return (EXTATTR_CONTENT_SIZE(eap)); } - return(-1); + return (-1); } static int @@ -1380,9 +1367,11 @@ vop_deleteextattr { { struct inode *ip; struct fs *fs; - uint32_t ealength, ul; - int ealen, olen, eapad1, eapad2, error, i, easize; - u_char *eae, *p; + struct extattr *eap; + uint32_t ul; + int olen, error, i, easize; + u_char *eae; + void *tmp; ip = VTOI(ap->a_vp); fs = ITOFS(ip); @@ -1413,39 +1402,30 @@ vop_deleteextattr { if (error) return (error); - ealength = eapad1 = ealen = eapad2 = 0; - + /* CEM: delete could be done in-place instead */ eae = malloc(ip->i_ea_len, M_TEMP, M_WAITOK); bcopy(ip->i_ea_area, eae, ip->i_ea_len); easize = ip->i_ea_len; olen = ffs_findextattr(eae, easize, ap->a_attrnamespace, ap->a_name, - &p, NULL); + &eap, NULL); if (olen == -1) { /* delete but nonexistent */ free(eae, M_TEMP); ffs_close_ea(ap->a_vp, 0, ap->a_cred, ap->a_td); - return(ENOATTR); + return (ENOATTR); } - bcopy(p, &ul, sizeof ul); - i = p - eae + ul; - if (ul != ealength) { - bcopy(p + ul, p + ealength, easize - i); - easize += (ealength - ul); - } - if (easize > NXADDR * fs->fs_bsize) { - free(eae, M_TEMP); - ffs_close_ea(ap->a_vp, 0, ap->a_cred, ap->a_td); - if (ip->i_ea_area != NULL && ip->i_ea_error == 0) - ip->i_ea_error = ENOSPC; - return(ENOSPC); - } - p = ip->i_ea_area; + ul = eap->ea_length; + i = (u_char *)EXTATTR_NEXT(eap) - eae; + bcopy(EXTATTR_NEXT(eap), eap, easize - i); + easize -= ul; + + tmp = ip->i_ea_area; ip->i_ea_area = eae; ip->i_ea_len = easize; - free(p, M_TEMP); + free(tmp, M_TEMP); error = ffs_close_ea(ap->a_vp, 1, ap->a_cred, ap->a_td); - return(error); + return (error); } /* @@ -1499,7 +1479,7 @@ vop_getextattr { error = ENOATTR; ffs_close_ea(ap->a_vp, 0, ap->a_cred, ap->a_td); - return(error); + return (error); } /* @@ -1519,9 +1499,7 @@ vop_listextattr { */ { struct inode *ip; - u_char *eae, *p, *pe, *pn; - unsigned easize; - uint32_t ul; + struct extattr *eap, *eaend; int error, ealen; ip = VTOI(ap->a_vp); @@ -1537,31 +1515,31 @@ vop_listextattr { error = ffs_open_ea(ap->a_vp, ap->a_cred, ap->a_td); if (error) return (error); - eae = ip->i_ea_area; - easize = ip->i_ea_len; error = 0; if (ap->a_size != NULL) *ap->a_size = 0; - pe = eae + easize; - for(p = eae; error == 0 && p < pe; p = pn) { - bcopy(p, &ul, sizeof(ul)); - pn = p + ul; - if (pn > pe) + + KASSERT(ALIGNED_TO(ip->i_ea_area, struct extattr), ("unaligned")); + eap = (struct extattr *)ip->i_ea_area; + eaend = (struct extattr *)(ip->i_ea_area + ip->i_ea_len); + for (; error == 0 && eap < eaend; eap = EXTATTR_NEXT(eap)) { + /* make sure this entry is complete */ + if (EXTATTR_NEXT(eap) > eaend) break; - p += sizeof(ul); - if (*p++ != ap->a_attrnamespace) + if (eap->ea_namespace != ap->a_attrnamespace) continue; - p++; /* pad2 */ - ealen = *p; - if (ap->a_size != NULL) { + + ealen = eap->ea_namelength; + if (ap->a_size != NULL) *ap->a_size += ealen + 1; - } else if (ap->a_uio != NULL) { - error = uiomove(p, ealen + 1, ap->a_uio); - } + else if (ap->a_uio != NULL) + error = uiomove(&eap->ea_namelength, ealen + 1, + ap->a_uio); } + ffs_close_ea(ap->a_vp, 0, ap->a_cred, ap->a_td); - return(error); + return (error); } /* @@ -1582,10 +1560,12 @@ vop_setextattr { { struct inode *ip; struct fs *fs; + struct extattr *eap; uint32_t ealength, ul; ssize_t ealen; int olen, eapad1, eapad2, error, i, easize; - u_char *eae, *p; + u_char *eae; + void *tmp; ip = VTOI(ap->a_vp); fs = ITOFS(ip); @@ -1625,29 +1605,33 @@ vop_setextattr { return (error); ealength = sizeof(uint32_t) + 3 + strlen(ap->a_name); - eapad1 = 8 - (ealength % 8); - if (eapad1 == 8) - eapad1 = 0; - eapad2 = 8 - (ealen % 8); - if (eapad2 == 8) - eapad2 = 0; + eapad1 = roundup2(ealength, 8) - ealength; + eapad2 = roundup2(ealen, 8) - ealen; ealength += eapad1 + ealen + eapad2; + /* + * CEM: rewrites of the same size or smaller could be done in-place + * instead. (We don't acquire any fine-grained locks in here either, + * so we could also do bigger writes in-place.) + */ eae = malloc(ip->i_ea_len + ealength, M_TEMP, M_WAITOK); bcopy(ip->i_ea_area, eae, ip->i_ea_len); easize = ip->i_ea_len; - olen = ffs_findextattr(eae, easize, - ap->a_attrnamespace, ap->a_name, &p, NULL); + olen = ffs_findextattr(eae, easize, ap->a_attrnamespace, ap->a_name, + &eap, NULL); if (olen == -1) { /* new, append at end */ - p = eae + easize; + KASSERT(ALIGNED_TO(eae + easize, struct extattr), + ("unaligned")); + eap = (struct extattr *)(eae + easize); easize += ealength; } else { - bcopy(p, &ul, sizeof ul); - i = p - eae + ul; + ul = eap->ea_length; + i = (u_char *)EXTATTR_NEXT(eap) - eae; if (ul != ealength) { - bcopy(p + ul, p + ealength, easize - i); + bcopy(EXTATTR_NEXT(eap), (u_char *)eap + ealength, + easize - i); easize += (ealength - ul); } } @@ -1656,34 +1640,30 @@ vop_setextattr { ffs_close_ea(ap->a_vp, 0, ap->a_cred, ap->a_td); if (ip->i_ea_area != NULL && ip->i_ea_error == 0) ip->i_ea_error = ENOSPC; - return(ENOSPC); + return (ENOSPC); } - bcopy(&ealength, p, sizeof(ealength)); - p += sizeof(ealength); - *p++ = ap->a_attrnamespace; - *p++ = eapad2; - *p++ = strlen(ap->a_name); - strcpy(p, ap->a_name); - p += strlen(ap->a_name); - bzero(p, eapad1); - p += eapad1; - error = uiomove(p, ealen, ap->a_uio); + eap->ea_length = ealength; + eap->ea_namespace = ap->a_attrnamespace; + eap->ea_contentpadlen = eapad2; + eap->ea_namelength = strlen(ap->a_name); + memcpy(eap->ea_name, ap->a_name, strlen(ap->a_name)); + bzero(&eap->ea_name[strlen(ap->a_name)], eapad1); + error = uiomove(EXTATTR_CONTENT(eap), ealen, ap->a_uio); if (error) { free(eae, M_TEMP); ffs_close_ea(ap->a_vp, 0, ap->a_cred, ap->a_td); if (ip->i_ea_area != NULL && ip->i_ea_error == 0) ip->i_ea_error = error; - return(error); + return (error); } - p += ealen; - bzero(p, eapad2); + bzero((u_char *)EXTATTR_CONTENT(eap) + ealen, eapad2); - p = ip->i_ea_area; + tmp = ip->i_ea_area; ip->i_ea_area = eae; ip->i_ea_len = easize; - free(p, M_TEMP); + free(tmp, M_TEMP); error = ffs_close_ea(ap->a_vp, 1, ap->a_cred, ap->a_td); - return(error); + return (error); } /*