From 669ced09b3b6070d478acce51810591b78ab0ccd Mon Sep 17 00:00:00 2001 From: Christian Schoenebeck Date: Wed, 22 Sep 2021 15:13:31 +0200 Subject: [PATCH 1/8] 9pfs: fix wrong I/O block size in Rgetattr When client sent a 9p Tgetattr request then the wrong I/O block size value was returned by 9p server; instead of host file system's I/O block size it should rather return an I/O block size according to 9p session's 'msize' value, because the value returned to client should be an "optimum" block size for I/O (i.e. to maximize performance), it should not reflect the actual physical block size of the underlying storage media. The I/O block size of a host filesystem is typically 4k, so the value returned was far too low for good 9p I/O performance. This patch adds stat_to_iounit() with a similar approach as the existing get_iounit() function. Signed-off-by: Christian Schoenebeck Reviewed-by: Greg Kurz Message-Id: --- hw/9pfs/9p.c | 21 ++++++++++++++++++++- 1 file changed, 20 insertions(+), 1 deletion(-) diff --git a/hw/9pfs/9p.c b/hw/9pfs/9p.c index c857b31321..708b030474 100644 --- a/hw/9pfs/9p.c +++ b/hw/9pfs/9p.c @@ -1262,6 +1262,25 @@ static int coroutine_fn stat_to_v9stat(V9fsPDU *pdu, V9fsPath *path, #define P9_STATS_ALL 0x00003fffULL /* Mask for All fields above */ +static int32_t stat_to_iounit(const V9fsPDU *pdu, const struct stat *stbuf) +{ + int32_t iounit = 0; + V9fsState *s = pdu->s; + + /* + * iounit should be multiples of st_blksize (host filesystem block size) + * as well as less than (client msize - P9_IOHDRSZ) + */ + if (stbuf->st_blksize) { + iounit = stbuf->st_blksize; + iounit *= (s->msize - P9_IOHDRSZ) / stbuf->st_blksize; + } + if (!iounit) { + iounit = s->msize - P9_IOHDRSZ; + } + return iounit; +} + static int stat_to_v9stat_dotl(V9fsPDU *pdu, const struct stat *stbuf, V9fsStatDotl *v9lstat) { @@ -1273,7 +1292,7 @@ static int stat_to_v9stat_dotl(V9fsPDU *pdu, const struct stat *stbuf, v9lstat->st_gid = stbuf->st_gid; v9lstat->st_rdev = stbuf->st_rdev; v9lstat->st_size = stbuf->st_size; - v9lstat->st_blksize = stbuf->st_blksize; + v9lstat->st_blksize = stat_to_iounit(pdu, stbuf); v9lstat->st_blocks = stbuf->st_blocks; v9lstat->st_atime_sec = stbuf->st_atime; v9lstat->st_atime_nsec = stbuf->st_atim.tv_nsec; From b565bccb00afe8b73d529bbc3a38682996dac5c7 Mon Sep 17 00:00:00 2001 From: Christian Schoenebeck Date: Mon, 27 Sep 2021 17:45:00 +0200 Subject: [PATCH 2/8] 9pfs: deduplicate iounit code Remove redundant code that translates host fileystem's block size into 9p client (guest side) block size. Signed-off-by: Christian Schoenebeck Reviewed-by: Greg Kurz Message-Id: <129bb71d5119e61d335f1e3107e472e4beea223a.1632758315.git.qemu_oss@crudebyte.com> --- hw/9pfs/9p.c | 41 ++++++++++++++++++++--------------------- 1 file changed, 20 insertions(+), 21 deletions(-) diff --git a/hw/9pfs/9p.c b/hw/9pfs/9p.c index 708b030474..5c57344667 100644 --- a/hw/9pfs/9p.c +++ b/hw/9pfs/9p.c @@ -1262,18 +1262,26 @@ static int coroutine_fn stat_to_v9stat(V9fsPDU *pdu, V9fsPath *path, #define P9_STATS_ALL 0x00003fffULL /* Mask for All fields above */ -static int32_t stat_to_iounit(const V9fsPDU *pdu, const struct stat *stbuf) +/** + * Convert host filesystem's block size into an appropriate block size for + * 9p client (guest OS side). The value returned suggests an "optimum" block + * size for 9p I/O, i.e. to maximize performance. + * + * @pdu: 9p client request + * @blksize: host filesystem's block size + */ +static int32_t blksize_to_iounit(const V9fsPDU *pdu, int32_t blksize) { int32_t iounit = 0; V9fsState *s = pdu->s; /* - * iounit should be multiples of st_blksize (host filesystem block size) + * iounit should be multiples of blksize (host filesystem block size) * as well as less than (client msize - P9_IOHDRSZ) */ - if (stbuf->st_blksize) { - iounit = stbuf->st_blksize; - iounit *= (s->msize - P9_IOHDRSZ) / stbuf->st_blksize; + if (blksize) { + iounit = blksize; + iounit *= (s->msize - P9_IOHDRSZ) / blksize; } if (!iounit) { iounit = s->msize - P9_IOHDRSZ; @@ -1281,6 +1289,11 @@ static int32_t stat_to_iounit(const V9fsPDU *pdu, const struct stat *stbuf) return iounit; } +static int32_t stat_to_iounit(const V9fsPDU *pdu, const struct stat *stbuf) +{ + return blksize_to_iounit(pdu, stbuf->st_blksize); +} + static int stat_to_v9stat_dotl(V9fsPDU *pdu, const struct stat *stbuf, V9fsStatDotl *v9lstat) { @@ -1899,23 +1912,9 @@ out_nofid: static int32_t coroutine_fn get_iounit(V9fsPDU *pdu, V9fsPath *path) { struct statfs stbuf; - int32_t iounit = 0; - V9fsState *s = pdu->s; + int err = v9fs_co_statfs(pdu, path, &stbuf); - /* - * iounit should be multiples of f_bsize (host filesystem block size - * and as well as less than (client msize - P9_IOHDRSZ)) - */ - if (!v9fs_co_statfs(pdu, path, &stbuf)) { - if (stbuf.f_bsize) { - iounit = stbuf.f_bsize; - iounit *= (s->msize - P9_IOHDRSZ) / stbuf.f_bsize; - } - } - if (!iounit) { - iounit = s->msize - P9_IOHDRSZ; - } - return iounit; + return blksize_to_iounit(pdu, (err >= 0) ? stbuf.f_bsize : 0); } static void coroutine_fn v9fs_open(void *opaque) From 04a7f9e55e0930b87805f7c97851eea4610e78fc Mon Sep 17 00:00:00 2001 From: Christian Schoenebeck Date: Mon, 27 Sep 2021 17:50:36 +0200 Subject: [PATCH 3/8] 9pfs: simplify blksize_to_iounit() MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Use QEMU_ALIGN_DOWN() macro to reduce code and to make it more human readable. Suggested-by: Philippe Mathieu-Daudé Signed-off-by: Christian Schoenebeck Reviewed-by: Greg Kurz Reviewed-by: Philippe Mathieu-Daudé Message-Id: --- hw/9pfs/9p.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/hw/9pfs/9p.c b/hw/9pfs/9p.c index 5c57344667..e874899ef5 100644 --- a/hw/9pfs/9p.c +++ b/hw/9pfs/9p.c @@ -1280,8 +1280,7 @@ static int32_t blksize_to_iounit(const V9fsPDU *pdu, int32_t blksize) * as well as less than (client msize - P9_IOHDRSZ) */ if (blksize) { - iounit = blksize; - iounit *= (s->msize - P9_IOHDRSZ) / blksize; + iounit = QEMU_ALIGN_DOWN(s->msize - P9_IOHDRSZ, blksize); } if (!iounit) { iounit = s->msize - P9_IOHDRSZ; From 30e702abf6fa8a7f1e6ad11a75d6f3ab6fcb2155 Mon Sep 17 00:00:00 2001 From: Christian Schoenebeck Date: Fri, 1 Oct 2021 16:26:17 +0200 Subject: [PATCH 4/8] 9pfs: introduce P9Array Implements deep auto free of arrays while retaining common C-style squared bracket access. Main purpose of this API is to get rid of error prone individual array deallocation pathes in user code, i.e. turning something like this: void doSomething(size_t n) { Foo *foos = malloc(n * sizeof(Foo)); for (...) { foos[i].s = malloc(...); if (...) { goto out; } } out: if (...) { for (...) { /* deep deallocation */ free(foos[i].s); } /* array deallocation */ free(foos); } } into something more simple and safer like: void doSomething(size_t n) { P9ARRAY_REF(Foo) foos = NULL; P9ARRAY_NEW(Foo, foos, n); for (...) { foos[i].s = malloc(...); if (...) { return; /* array auto freed here */ } } /* array auto freed here */ } Unlike GArray, P9Array does not require special macros, function calls or struct member dereferencing to access the individual array elements: C-array = P9Array: vs. GArray: for (...) { | for (...) { ... = arr[i].m; | ... = g_array_index(arr, Foo, i).m; arr[i].m = ... ; | g_array_index(arr, Foo, i).m = ... ; } | } So existing C-style array code can be retained with only very little changes; basically limited to replacing array allocation call and of course removing individual array deallocation pathes. In this initial version P9Array only supports the concept of unique pointers, i.e. it does not support reference counting. The array (and all dynamically allocated memory of individual array elements) is auto freed once execution leaves the scope of the reference variable (unique pointer) associated with the array. Internally a flex array struct is used in combination with macros spanned over a continuous memory space for both the array's meta data (private) and the actual C-array user data (public): struct P9Array##scalar_type { size_t len; /* private, hidden from user code */ scalar_type first[]; /* public, directly exposed to user code */ }; Which has the advantage that the compiler automatically takes care about correct padding, alignment and overall size for all scalar data types on all systems and that the user space exposed pointer can directly be translated back and forth between user space C-array pointer and internal P9Array struct whenever needed, in a type-safe manner. This header file is released under MIT license, to allow this file being used in other C-projects as well. The common QEMU license GPL2+ might have construed a conflict for other projects. Signed-off-by: Christian Schoenebeck Message-Id: --- fsdev/p9array.h | 154 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 154 insertions(+) create mode 100644 fsdev/p9array.h diff --git a/fsdev/p9array.h b/fsdev/p9array.h new file mode 100644 index 0000000000..fff946a3d7 --- /dev/null +++ b/fsdev/p9array.h @@ -0,0 +1,154 @@ +/* + * P9Array - deep auto free C-array + * + * Copyright (c) 2021 Crudebyte + * + * Authors: + * Christian Schoenebeck + * + * Permission is hereby granted, free of charge, to any person obtaining a copy + * of this software and associated documentation files (the "Software"), to deal + * in the Software without restriction, including without limitation the rights + * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell + * copies of the Software, and to permit persons to whom the Software is + * furnished to do so, subject to the following conditions: + * + * The above copyright notice and this permission notice shall be included in + * all copies or substantial portions of the Software. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, + * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN + * THE SOFTWARE. + */ +#ifndef QEMU_P9ARRAY_H +#define QEMU_P9ARRAY_H + +/** + * P9Array provides a mechanism to access arrays in common C-style (e.g. by + * square bracket [] operator) in conjunction with reference variables that + * perform deep auto free of the array when leaving the scope of the auto + * reference variable. That means not only is the array itself automatically + * freed, but also memory dynamically allocated by the individual array + * elements. + * + * Example: + * + * Consider the following user struct @c Foo which shall be used as scalar + * (element) type of an array: + * @code + * typedef struct Foo { + * int i; + * char *s; + * } Foo; + * @endcode + * and assume it has the following function to free memory allocated by @c Foo + * instances: + * @code + * void free_foo(Foo *foo) { + * free(foo->s); + * } + * @endcode + * Add the following to a shared header file: + * @code + * P9ARRAY_DECLARE_TYPE(Foo); + * @endcode + * and the following to a C unit file: + * @code + * P9ARRAY_DEFINE_TYPE(Foo, free_foo); + * @endcode + * Finally the array may then be used like this: + * @code + * void doSomething(size_t n) { + * P9ARRAY_REF(Foo) foos = NULL; + * P9ARRAY_NEW(Foo, foos, n); + * for (size_t i = 0; i < n; ++i) { + * foos[i].i = i; + * foos[i].s = calloc(4096, 1); + * snprintf(foos[i].s, 4096, "foo %d", i); + * if (...) { + * return; // array auto freed here + * } + * } + * // array auto freed here + * } + * @endcode + */ + +/** + * Declares an array type for the passed @a scalar_type. + * + * This is typically used from a shared header file. + * + * @param scalar_type - type of the individual array elements + */ +#define P9ARRAY_DECLARE_TYPE(scalar_type) \ + typedef struct P9Array##scalar_type { \ + size_t len; \ + scalar_type first[]; \ + } P9Array##scalar_type; \ + \ + void p9array_new_##scalar_type(scalar_type **auto_var, size_t len); \ + void p9array_auto_free_##scalar_type(scalar_type **auto_var); \ + +/** + * Defines an array type for the passed @a scalar_type and appropriate + * @a scalar_cleanup_func. + * + * This is typically used from a C unit file. + * + * @param scalar_type - type of the individual array elements + * @param scalar_cleanup_func - appropriate function to free memory dynamically + * allocated by individual array elements before + */ +#define P9ARRAY_DEFINE_TYPE(scalar_type, scalar_cleanup_func) \ + void p9array_new_##scalar_type(scalar_type **auto_var, size_t len) \ + { \ + p9array_auto_free_##scalar_type(auto_var); \ + P9Array##scalar_type *arr = g_malloc0(sizeof(P9Array##scalar_type) + \ + len * sizeof(scalar_type)); \ + arr->len = len; \ + *auto_var = &arr->first[0]; \ + } \ + \ + void p9array_auto_free_##scalar_type(scalar_type **auto_var) \ + { \ + scalar_type *first = (*auto_var); \ + if (!first) { \ + return; \ + } \ + P9Array##scalar_type *arr = (P9Array##scalar_type *) ( \ + ((char *)first) - offsetof(P9Array##scalar_type, first) \ + ); \ + for (size_t i = 0; i < arr->len; ++i) { \ + scalar_cleanup_func(&arr->first[i]); \ + } \ + g_free(arr); \ + } \ + +/** + * Used to declare a reference variable (unique pointer) for an array. After + * leaving the scope of the reference variable, the associated array is + * automatically freed. + * + * @param scalar_type - type of the individual array elements + */ +#define P9ARRAY_REF(scalar_type) \ + __attribute((__cleanup__(p9array_auto_free_##scalar_type))) scalar_type* + +/** + * Allocates a new array of passed @a scalar_type with @a len number of array + * elements and assigns the created array to the reference variable + * @a auto_var. + * + * @param scalar_type - type of the individual array elements + * @param auto_var - destination reference variable + * @param len - amount of array elements to be allocated immediately + */ +#define P9ARRAY_NEW(scalar_type, auto_var, len) \ + p9array_new_##scalar_type((&auto_var), len) + +#endif /* QEMU_P9ARRAY_H */ From c0451f0bc4210d262268ff51c053a9277f20f862 Mon Sep 17 00:00:00 2001 From: Christian Schoenebeck Date: Fri, 1 Oct 2021 16:27:13 +0200 Subject: [PATCH 5/8] fsdev/p9array.h: check scalar type in P9ARRAY_NEW() Make sure at compile time that the scalar type of the array requested to be created via P9ARRAY_NEW() matches the scalar type of the passed auto reference variable (unique pointer). Suggested-by: Richard Henderson Signed-off-by: Christian Schoenebeck Message-Id: --- fsdev/p9array.h | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/fsdev/p9array.h b/fsdev/p9array.h index fff946a3d7..6aa25327ca 100644 --- a/fsdev/p9array.h +++ b/fsdev/p9array.h @@ -27,6 +27,8 @@ #ifndef QEMU_P9ARRAY_H #define QEMU_P9ARRAY_H +#include "qemu/compiler.h" + /** * P9Array provides a mechanism to access arrays in common C-style (e.g. by * square bracket [] operator) in conjunction with reference variables that @@ -149,6 +151,10 @@ * @param len - amount of array elements to be allocated immediately */ #define P9ARRAY_NEW(scalar_type, auto_var, len) \ + QEMU_BUILD_BUG_MSG( \ + !__builtin_types_compatible_p(scalar_type, typeof(*auto_var)), \ + "P9Array scalar type mismatch" \ + ); \ p9array_new_##scalar_type((&auto_var), len) #endif /* QEMU_P9ARRAY_H */ From 42bdeb04b6a4bf3e54f4d7f87193803268ba8255 Mon Sep 17 00:00:00 2001 From: Christian Schoenebeck Date: Fri, 1 Oct 2021 16:27:29 +0200 Subject: [PATCH 6/8] 9pfs: make V9fsString usable via P9Array API Signed-off-by: Christian Schoenebeck Message-Id: --- fsdev/9p-marshal.c | 2 ++ fsdev/9p-marshal.h | 3 +++ 2 files changed, 5 insertions(+) diff --git a/fsdev/9p-marshal.c b/fsdev/9p-marshal.c index a01bba6908..51881fe220 100644 --- a/fsdev/9p-marshal.c +++ b/fsdev/9p-marshal.c @@ -18,6 +18,8 @@ #include "9p-marshal.h" +P9ARRAY_DEFINE_TYPE(V9fsString, v9fs_string_free); + void v9fs_string_free(V9fsString *str) { g_free(str->data); diff --git a/fsdev/9p-marshal.h b/fsdev/9p-marshal.h index ceaf2f521e..f1abbe151c 100644 --- a/fsdev/9p-marshal.h +++ b/fsdev/9p-marshal.h @@ -1,10 +1,13 @@ #ifndef QEMU_9P_MARSHAL_H #define QEMU_9P_MARSHAL_H +#include "p9array.h" + typedef struct V9fsString { uint16_t size; char *data; } V9fsString; +P9ARRAY_DECLARE_TYPE(V9fsString); typedef struct V9fsQID { uint8_t type; From cc82fde9c7b4b598907914896ee6942fa866258c Mon Sep 17 00:00:00 2001 From: Christian Schoenebeck Date: Fri, 1 Oct 2021 16:27:46 +0200 Subject: [PATCH 7/8] 9pfs: make V9fsPath usable via P9Array API Signed-off-by: Christian Schoenebeck Message-Id: <79a0ddf8375f6c95f0565ef155a1bf1e9387664f.1633097129.git.qemu_oss@crudebyte.com> --- fsdev/file-op-9p.h | 2 ++ hw/9pfs/9p.c | 2 ++ 2 files changed, 4 insertions(+) diff --git a/fsdev/file-op-9p.h b/fsdev/file-op-9p.h index 42f677cf38..8fd89f0447 100644 --- a/fsdev/file-op-9p.h +++ b/fsdev/file-op-9p.h @@ -18,6 +18,7 @@ #include #include #include "qemu-fsdev-throttle.h" +#include "p9array.h" #define SM_LOCAL_MODE_BITS 0600 #define SM_LOCAL_DIR_MODE_BITS 0700 @@ -105,6 +106,7 @@ struct V9fsPath { uint16_t size; char *data; }; +P9ARRAY_DECLARE_TYPE(V9fsPath); typedef union V9fsFidOpenState V9fsFidOpenState; diff --git a/hw/9pfs/9p.c b/hw/9pfs/9p.c index e874899ef5..15bb16f466 100644 --- a/hw/9pfs/9p.c +++ b/hw/9pfs/9p.c @@ -50,6 +50,8 @@ enum { Oappend = 0x80, }; +P9ARRAY_DEFINE_TYPE(V9fsPath, v9fs_path_free); + static ssize_t pdu_marshal(V9fsPDU *pdu, size_t offset, const char *fmt, ...) { ssize_t ret; From 7e985780aaab93d2c5be9b62d8d386568dfb071e Mon Sep 17 00:00:00 2001 From: Christian Schoenebeck Date: Fri, 1 Oct 2021 16:27:59 +0200 Subject: [PATCH 8/8] 9pfs: use P9Array in v9fs_walk() Signed-off-by: Christian Schoenebeck Message-Id: <90c65d1c1ca11c1b434bb981b1fc7966f7711c8f.1633097129.git.qemu_oss@crudebyte.com> --- hw/9pfs/9p.c | 17 +++++------------ 1 file changed, 5 insertions(+), 12 deletions(-) diff --git a/hw/9pfs/9p.c b/hw/9pfs/9p.c index 15bb16f466..15b3f4d385 100644 --- a/hw/9pfs/9p.c +++ b/hw/9pfs/9p.c @@ -1738,13 +1738,14 @@ static void coroutine_fn v9fs_walk(void *opaque) int name_idx; g_autofree V9fsQID *qids = NULL; int i, err = 0; - V9fsPath dpath, path, *pathes = NULL; + V9fsPath dpath, path; + P9ARRAY_REF(V9fsPath) pathes = NULL; uint16_t nwnames; struct stat stbuf, fidst; g_autofree struct stat *stbufs = NULL; size_t offset = 7; int32_t fid, newfid; - V9fsString *wnames = NULL; + P9ARRAY_REF(V9fsString) wnames = NULL; V9fsFidState *fidp; V9fsFidState *newfidp = NULL; V9fsPDU *pdu = opaque; @@ -1765,10 +1766,10 @@ static void coroutine_fn v9fs_walk(void *opaque) goto out_nofid; } if (nwnames) { - wnames = g_new0(V9fsString, nwnames); + P9ARRAY_NEW(V9fsString, wnames, nwnames); qids = g_new0(V9fsQID, nwnames); stbufs = g_new0(struct stat, nwnames); - pathes = g_new0(V9fsPath, nwnames); + P9ARRAY_NEW(V9fsPath, pathes, nwnames); for (i = 0; i < nwnames; i++) { err = pdu_unmarshal(pdu, offset, "s", &wnames[i]); if (err < 0) { @@ -1900,14 +1901,6 @@ out: v9fs_path_free(&path); out_nofid: pdu_complete(pdu, err); - if (nwnames && nwnames <= P9_MAXWELEM) { - for (name_idx = 0; name_idx < nwnames; name_idx++) { - v9fs_string_free(&wnames[name_idx]); - v9fs_path_free(&pathes[name_idx]); - } - g_free(wnames); - g_free(pathes); - } } static int32_t coroutine_fn get_iounit(V9fsPDU *pdu, V9fsPath *path)