[lvm-devel] master - device: Introduce dev_read_callback
Alasdair Kergon
agk at sourceware.org
Sat Jan 6 02:43:29 UTC 2018
Gitweb: https://sourceware.org/git/?p=lvm2.git;a=commitdiff;h=5e7d3ad749d3de735ba213ad64637182afec2586
Commit: 5e7d3ad749d3de735ba213ad64637182afec2586
Parent: 946f07af3e8f97b0e48752ce1cd8de87d3456540
Author: Alasdair G Kergon <agk at redhat.com>
AuthorDate: Sat Jan 6 00:33:09 2018 +0000
Committer: Alasdair G Kergon <agk at redhat.com>
CommitterDate: Sat Jan 6 02:40:12 2018 +0000
device: Introduce dev_read_callback
If it obtains the data, it passes it into the supplied callback function
and returns 1. Otherwise the callback receives failed = 1.
Updated config_file_read_fd to use this and similarly return the data
via a callback fn of its own.
---
WHATS_NEW | 1 +
lib/config/config.c | 72 ++++++++++++++++++++++++++--------------------
lib/config/config.h | 4 ++-
lib/device/dev-io.c | 27 +++++++++++++++++
lib/device/device.h | 8 ++++-
lib/format_text/import.c | 39 +++++++++++++-----------
6 files changed, 100 insertions(+), 51 deletions(-)
diff --git a/WHATS_NEW b/WHATS_NEW
index fa79068..345c472 100644
--- a/WHATS_NEW
+++ b/WHATS_NEW
@@ -1,5 +1,6 @@
Version 2.02.178 -
=====================================
+ Refactor metadata reading code to use callback functions.
Move memory allocation for the key dev_reads into the device layer.
Version 2.02.177 - 18th December 2017
diff --git a/lib/config/config.c b/lib/config/config.c
index bffee06..7217cd9 100644
--- a/lib/config/config.c
+++ b/lib/config/config.c
@@ -500,16 +500,21 @@ struct process_config_file_params {
uint32_t checksum;
int checksum_only;
int no_dup_node_check;
+ int use_mmap;
+ lvm_callback_fn_t config_file_read_fd_callback;
+ void *config_file_read_fd_context;
int ret;
};
static void _process_config_file_buffer(int failed, void *context, void *data)
{
struct process_config_file_params *pcfp = context;
- char *buffer = data;
- char *fb, *fe;
+ char *fb = data, *fe;
- fb = buffer;
+ if (failed) {
+ pcfp->ret = 0;
+ goto_out;
+ }
if (pcfp->checksum_fn && pcfp->checksum !=
(pcfp->checksum_fn(pcfp->checksum_fn(INITIAL_CRC, (const uint8_t *)fb, pcfp->size),
@@ -529,7 +534,11 @@ static void _process_config_file_buffer(int failed, void *context, void *data)
}
out:
- ;
+ if (!failed && !pcfp->use_mmap)
+ dm_free(data);
+
+ if (pcfp->config_file_read_fd_callback)
+ pcfp->config_file_read_fd_callback(!pcfp->ret, pcfp->config_file_read_fd_context, NULL);
}
/*
@@ -540,11 +549,11 @@ out:
int config_file_read_fd(struct dm_pool *mem, struct dm_config_tree *cft, struct device *dev, dev_io_reason_t reason,
off_t offset, size_t size, off_t offset2, size_t size2,
checksum_fn_t checksum_fn, uint32_t checksum,
- int checksum_only, int no_dup_node_check)
+ int checksum_only, int no_dup_node_check,
+ lvm_callback_fn_t config_file_read_fd_callback, void *config_file_read_fd_context)
{
char *fb;
int r = 0;
- int use_mmap = 1;
off_t mmap_offset = 0;
char *buf = NULL;
unsigned circular = size2 ? 1 : 0; /* Wrapped around end of disk metadata buffer? */
@@ -555,12 +564,12 @@ int config_file_read_fd(struct dm_pool *mem, struct dm_config_tree *cft, struct
log_error(INTERNAL_ERROR "config_file_read_fd: expected file, special file "
"or profile config source, found %s config source.",
_config_source_names[cs->type]);
- return 0;
+ goto bad;
}
if (!(pcfp = dm_pool_zalloc(mem, sizeof(*pcfp)))) {
log_debug("config_file_read_fd: process_config_file_params struct allocation failed");
- return 0;
+ goto bad;
}
pcfp->cft = cft;
@@ -573,48 +582,49 @@ int config_file_read_fd(struct dm_pool *mem, struct dm_config_tree *cft, struct
pcfp->checksum = checksum;
pcfp->checksum_only = checksum_only;
pcfp->no_dup_node_check = no_dup_node_check;
+ pcfp->config_file_read_fd_callback = config_file_read_fd_callback;
+ pcfp->config_file_read_fd_context = config_file_read_fd_context;
+ pcfp->use_mmap = 1;
pcfp->ret = 1;
/* Only use mmap with regular files */
if (!(dev->flags & DEV_REGULAR) || circular)
- use_mmap = 0;
+ pcfp->use_mmap = 0;
- if (use_mmap) {
+ if (pcfp->use_mmap) {
mmap_offset = offset % lvm_getpagesize();
/* memory map the file */
fb = mmap((caddr_t) 0, size + mmap_offset, PROT_READ,
MAP_PRIVATE, dev_fd(dev), offset - mmap_offset);
if (fb == (caddr_t) (-1)) {
log_sys_error("mmap", dev_name(dev));
- goto out;
+ goto bad;
+ }
+ _process_config_file_buffer(0, pcfp, fb + mmap_offset);
+ r = pcfp->ret;
+ /* unmap the file */
+ if (munmap(fb, size + mmap_offset)) {
+ log_sys_error("munmap", dev_name(dev));
+ r = 0;
}
- fb = fb + mmap_offset;
} else {
if (circular) {
if (!(buf = dev_read_circular(dev, (uint64_t) offset, size, (uint64_t) offset2, size2, reason)))
goto_out;
- } else {
- if (!(buf = dev_read(dev, (uint64_t) offset, size, reason)))
- goto_out;
- }
- fb = buf;
+ _process_config_file_buffer(0, pcfp, buf);
+ } else if (!dev_read_callback(dev, (uint64_t) offset, size, reason, _process_config_file_buffer, pcfp))
+ goto_out;
+ r = pcfp->ret;
}
- _process_config_file_buffer(0, pcfp, fb);
- r = pcfp->ret;
+out:
+ return r;
- out:
- if (!use_mmap)
- dm_free(buf);
- else {
- /* unmap the file */
- if (munmap(fb - mmap_offset, size + mmap_offset)) {
- log_sys_error("munmap", dev_name(dev));
- r = 0;
- }
- }
+bad:
+ if (config_file_read_fd_callback)
+ config_file_read_fd_callback(1, config_file_read_fd_context, NULL);
- return r;
+ return 0;
}
int config_file_read(struct dm_pool *mem, struct dm_config_tree *cft)
@@ -646,7 +656,7 @@ int config_file_read(struct dm_pool *mem, struct dm_config_tree *cft)
}
r = config_file_read_fd(mem, cft, cf->dev, DEV_IO_MDA_CONTENT, 0, (size_t) info.st_size, 0, 0,
- (checksum_fn_t) NULL, 0, 0, 0);
+ (checksum_fn_t) NULL, 0, 0, 0, NULL, NULL);
if (!cf->keep_open) {
if (!dev_close(cf->dev))
diff --git a/lib/config/config.h b/lib/config/config.h
index 5c8844a..9901003 100644
--- a/lib/config/config.h
+++ b/lib/config/config.h
@@ -242,7 +242,9 @@ struct dm_config_tree *config_open(config_source_t source, const char *filename,
int config_file_read_fd(struct dm_pool *mem, struct dm_config_tree *cft, struct device *dev, dev_io_reason_t reason,
off_t offset, size_t size, off_t offset2, size_t size2,
checksum_fn_t checksum_fn, uint32_t checksum,
- int skip_parse, int no_dup_node_check);
+ int skip_parse, int no_dup_node_check,
+ lvm_callback_fn_t config_file_read_fd_callback, void *config_file_read_fd_context);
+
int config_file_read(struct dm_pool *mem, struct dm_config_tree *cft);
struct dm_config_tree *config_file_open_and_read(const char *config_file, config_source_t source,
struct cmd_context *cmd);
diff --git a/lib/device/dev-io.c b/lib/device/dev-io.c
index 72d6768..22a0d4c 100644
--- a/lib/device/dev-io.c
+++ b/lib/device/dev-io.c
@@ -763,6 +763,33 @@ char *dev_read(struct device *dev, uint64_t offset, size_t len, dev_io_reason_t
return buf;
}
+/* Callback fn is responsible for dm_free */
+int dev_read_callback(struct device *dev, uint64_t offset, size_t len, dev_io_reason_t reason,
+ lvm_callback_fn_t dev_read_callback_fn, void *callback_context)
+{
+ char *buf;
+ int r = 0;
+
+ if (!(buf = dm_malloc(len))) {
+ log_error("Buffer allocation failed for device read.");
+ goto out;
+ }
+
+ if (!_dev_read(dev, offset, len, reason, buf)) {
+ log_error("Read from %s failed", dev_name(dev));
+ dm_free(buf);
+ goto out;
+ }
+
+ r = 1;
+
+out:
+ if (dev_read_callback_fn)
+ dev_read_callback_fn(!r, callback_context, buf);
+
+ return r;
+}
+
/* Read into supplied retbuf */
int dev_read_buf(struct device *dev, uint64_t offset, size_t len, dev_io_reason_t reason, void *retbuf)
{
diff --git a/lib/device/device.h b/lib/device/device.h
index 04117d2..4349222 100644
--- a/lib/device/device.h
+++ b/lib/device/device.h
@@ -33,7 +33,9 @@
#define DEV_NOT_O_NOATIME 0x00000400 /* Don't use O_NOATIME */
/*
- * Standard format for callback functions
+ * Standard format for callback functions.
+ * When provided, callback functions are called exactly once.
+ * If failed is set, data cannot be accessed.
*/
typedef void (*lvm_callback_fn_t)(int failed, void *context, void *data);
@@ -155,6 +157,10 @@ char *dev_read(struct device *dev, uint64_t offset, size_t len, dev_io_reason_t
char *dev_read_circular(struct device *dev, uint64_t offset, size_t len,
uint64_t offset2, size_t len2, dev_io_reason_t reason);
+/* Passes the data to dev_read_callback_fn */
+int dev_read_callback(struct device *dev, uint64_t offset, size_t len, dev_io_reason_t reason,
+ lvm_callback_fn_t dev_read_callback_fn, void *callback_context);
+
/* Read data and copy it into a supplied private buffer. */
/* Only use for tiny reads or on unimportant code paths. */
int dev_read_buf(struct device *dev, uint64_t offset, size_t len, dev_io_reason_t reason, void *retbuf);
diff --git a/lib/format_text/import.c b/lib/format_text/import.c
index 64ef2be..a295b78 100644
--- a/lib/format_text/import.c
+++ b/lib/format_text/import.c
@@ -46,6 +46,11 @@ static void _import_vgsummary(int failed, void *context, void *data)
struct import_vgsummary_params *ivsp = context;
struct text_vg_version_ops **vsn;
+ if (failed) {
+ ivsp->ret = 0;
+ goto_out;
+ }
+
if (ivsp->checksum_only)
/* Checksum matches already-cached content - no need to reparse. */
goto out;
@@ -100,23 +105,20 @@ int text_vgsummary_import(const struct format_type *fmt,
ivsp->vgsummary = vgsummary;
ivsp->ret = 1;
- if (!dev && !config_file_read(fmt->cmd->mem, ivsp->cft)) {
- log_error("Couldn't read volume group metadata.");
- config_destroy(ivsp->cft);
- return 0;
- }
-
- if (dev && !config_file_read_fd(fmt->cmd->mem, ivsp->cft, dev, reason, offset, size,
+ if (!dev) {
+ if (!config_file_read(fmt->cmd->mem, ivsp->cft)) {
+ log_error("Couldn't read volume group metadata.");
+ ivsp->ret = 0;
+ }
+ _import_vgsummary(!ivsp->ret, ivsp, NULL);
+ } else if (!config_file_read_fd(fmt->cmd->mem, ivsp->cft, dev, reason, offset, size,
offset2, size2, checksum_fn,
vgsummary->mda_checksum,
- checksum_only, 1)) {
+ checksum_only, 1, &_import_vgsummary, ivsp)) {
log_error("Couldn't read volume group metadata.");
- config_destroy(ivsp->cft);
return 0;
}
- _import_vgsummary(0, ivsp, NULL);
-
return ivsp->ret;
}
@@ -229,14 +231,15 @@ struct volume_group *text_vg_import_fd(struct format_instance *fid,
return_NULL;
}
- if (dev && !config_file_read_fd(fid->mem, ivp->cft, dev, MDA_CONTENT_REASON(primary_mda), offset, size,
+ if (dev) {
+ if (!config_file_read_fd(fid->mem, ivp->cft, dev, MDA_CONTENT_REASON(primary_mda), offset, size,
offset2, size2, checksum_fn, checksum,
- ivp->skip_parse, 1)) {
- config_destroy(ivp->cft);
- return_NULL;
- }
-
- _import_vg(0, ivp, NULL);
+ ivp->skip_parse, 1, &_import_vg, ivp)) {
+ config_destroy(ivp->cft);
+ return_NULL;
+ }
+ } else
+ _import_vg(0, ivp, NULL);
return ivp->vg;
}
More information about the lvm-devel
mailing list