Revision a742994aa2e271eb8cd8e043d276515ec858ed73 authored by Filipe Manana on 13 February 2015, 16:56:14 UTC, committed by Chris Mason on 14 February 2015, 16:22:49 UTC
If we are recording in the tree log that an inode has new names (new hard links were added), we would drop items, belonging to the inode, that we shouldn't: 1) When the flag BTRFS_INODE_COPY_EVERYTHING is set in the inode's runtime flags, we ended up dropping all the extent and xattr items that were previously logged. This was done only in memory, since logging a new name doesn't imply syncing the log; 2) When the flag BTRFS_INODE_COPY_EVERYTHING is set in the inode's runtime flags, we ended up dropping all the xattr items that were previously logged. Like the case before, this was done only in memory because logging a new name doesn't imply syncing the log. This led to some surprises in scenarios such as the following: 1) write some extents to an inode; 2) fsync the inode; 3) truncate the inode or delete/modify some of its xattrs 4) add a new hard link for that inode 5) fsync some other file, to force the log tree to be durably persisted 6) power failure happens The next time the fs is mounted, the fsync log replay code is executed, and the resulting file doesn't have the content it had when the last fsync against it was performed, instead if has a content matching what it had when the last transaction commit happened. So change the behaviour such that when a new name is logged, only the inode item and reference items are processed. This is easy to reproduce with the test I just made for xfstests, whose main body is: _scratch_mkfs >> $seqres.full 2>&1 _init_flakey _mount_flakey # Create our test file with some data. $XFS_IO_PROG -f -c "pwrite -S 0xaa -b 8K 0 8K" \ $SCRATCH_MNT/foo | _filter_xfs_io # Make sure the file is durably persisted. sync # Append some data to our file, to increase its size. $XFS_IO_PROG -f -c "pwrite -S 0xcc -b 4K 8K 4K" \ $SCRATCH_MNT/foo | _filter_xfs_io # Fsync the file, so from this point on if a crash/power failure happens, our # new data is guaranteed to be there next time the fs is mounted. $XFS_IO_PROG -c "fsync" $SCRATCH_MNT/foo # Now shrink our file to 5000 bytes. $XFS_IO_PROG -c "truncate 5000" $SCRATCH_MNT/foo # Now do an expanding truncate to a size larger than what we had when we last # fsync'ed our file. This is just to verify that after power failure and # replaying the fsync log, our file matches what it was when we last fsync'ed # it - 12Kb size, first 8Kb of data had a value of 0xaa and the last 4Kb of # data had a value of 0xcc. $XFS_IO_PROG -c "truncate 32K" $SCRATCH_MNT/foo # Add one hard link to our file. This made btrfs drop all of our file's # metadata from the fsync log, including the metadata relative to the # extent we just wrote and fsync'ed. This change was made only to the fsync # log in memory, so adding the hard link alone doesn't change the persisted # fsync log. This happened because the previous truncates set the runtime # flag BTRFS_INODE_NEEDS_FULL_SYNC in the btrfs inode structure. ln $SCRATCH_MNT/foo $SCRATCH_MNT/foo_link # Now make sure the in memory fsync log is durably persisted. # Creating and fsync'ing another file will do it. # After this our persisted fsync log will no longer have metadata for our file # foo that points to the extent we wrote and fsync'ed before. touch $SCRATCH_MNT/bar $XFS_IO_PROG -c "fsync" $SCRATCH_MNT/bar # As expected, before the crash/power failure, we should be able to see a file # with a size of 32Kb, with its first 5000 bytes having the value 0xaa and all # the remaining bytes with value 0x00. echo "File content before:" od -t x1 $SCRATCH_MNT/foo # Simulate a crash/power loss. _load_flakey_table $FLAKEY_DROP_WRITES _unmount_flakey _load_flakey_table $FLAKEY_ALLOW_WRITES _mount_flakey # After mounting the fs again, the fsync log was replayed. # The expected result is to see a file with a size of 12Kb, with its first 8Kb # of data having the value 0xaa and its last 4Kb of data having a value of 0xcc. # The btrfs bug used to leave the file as it used te be as of the last # transaction commit - that is, with a size of 8Kb with all bytes having a # value of 0xaa. echo "File content after:" od -t x1 $SCRATCH_MNT/foo The test case for xfstests follows soon. Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: Chris Mason <clm@fb.com>
1 parent 1a4bcf4
parser.c
/*
* lib/parser.c - simple parser for mount, etc. options.
*
* This source code is licensed under the GNU General Public License,
* Version 2. See the file COPYING for more details.
*/
#include <linux/ctype.h>
#include <linux/types.h>
#include <linux/export.h>
#include <linux/parser.h>
#include <linux/slab.h>
#include <linux/string.h>
/**
* match_one: - Determines if a string matches a simple pattern
* @s: the string to examine for presence of the pattern
* @p: the string containing the pattern
* @args: array of %MAX_OPT_ARGS &substring_t elements. Used to return match
* locations.
*
* Description: Determines if the pattern @p is present in string @s. Can only
* match extremely simple token=arg style patterns. If the pattern is found,
* the location(s) of the arguments will be returned in the @args array.
*/
static int match_one(char *s, const char *p, substring_t args[])
{
char *meta;
int argc = 0;
if (!p)
return 1;
while(1) {
int len = -1;
meta = strchr(p, '%');
if (!meta)
return strcmp(p, s) == 0;
if (strncmp(p, s, meta-p))
return 0;
s += meta - p;
p = meta + 1;
if (isdigit(*p))
len = simple_strtoul(p, (char **) &p, 10);
else if (*p == '%') {
if (*s++ != '%')
return 0;
p++;
continue;
}
if (argc >= MAX_OPT_ARGS)
return 0;
args[argc].from = s;
switch (*p++) {
case 's': {
size_t str_len = strlen(s);
if (str_len == 0)
return 0;
if (len == -1 || len > str_len)
len = str_len;
args[argc].to = s + len;
break;
}
case 'd':
simple_strtol(s, &args[argc].to, 0);
goto num;
case 'u':
simple_strtoul(s, &args[argc].to, 0);
goto num;
case 'o':
simple_strtoul(s, &args[argc].to, 8);
goto num;
case 'x':
simple_strtoul(s, &args[argc].to, 16);
num:
if (args[argc].to == args[argc].from)
return 0;
break;
default:
return 0;
}
s = args[argc].to;
argc++;
}
}
/**
* match_token: - Find a token (and optional args) in a string
* @s: the string to examine for token/argument pairs
* @table: match_table_t describing the set of allowed option tokens and the
* arguments that may be associated with them. Must be terminated with a
* &struct match_token whose pattern is set to the NULL pointer.
* @args: array of %MAX_OPT_ARGS &substring_t elements. Used to return match
* locations.
*
* Description: Detects which if any of a set of token strings has been passed
* to it. Tokens can include up to MAX_OPT_ARGS instances of basic c-style
* format identifiers which will be taken into account when matching the
* tokens, and whose locations will be returned in the @args array.
*/
int match_token(char *s, const match_table_t table, substring_t args[])
{
const struct match_token *p;
for (p = table; !match_one(s, p->pattern, args) ; p++)
;
return p->token;
}
EXPORT_SYMBOL(match_token);
/**
* match_number: scan a number in the given base from a substring_t
* @s: substring to be scanned
* @result: resulting integer on success
* @base: base to use when converting string
*
* Description: Given a &substring_t and a base, attempts to parse the substring
* as a number in that base. On success, sets @result to the integer represented
* by the string and returns 0. Returns -ENOMEM, -EINVAL, or -ERANGE on failure.
*/
static int match_number(substring_t *s, int *result, int base)
{
char *endp;
char *buf;
int ret;
long val;
size_t len = s->to - s->from;
buf = kmalloc(len + 1, GFP_KERNEL);
if (!buf)
return -ENOMEM;
memcpy(buf, s->from, len);
buf[len] = '\0';
ret = 0;
val = simple_strtol(buf, &endp, base);
if (endp == buf)
ret = -EINVAL;
else if (val < (long)INT_MIN || val > (long)INT_MAX)
ret = -ERANGE;
else
*result = (int) val;
kfree(buf);
return ret;
}
/**
* match_int: - scan a decimal representation of an integer from a substring_t
* @s: substring_t to be scanned
* @result: resulting integer on success
*
* Description: Attempts to parse the &substring_t @s as a decimal integer. On
* success, sets @result to the integer represented by the string and returns 0.
* Returns -ENOMEM, -EINVAL, or -ERANGE on failure.
*/
int match_int(substring_t *s, int *result)
{
return match_number(s, result, 0);
}
EXPORT_SYMBOL(match_int);
/**
* match_octal: - scan an octal representation of an integer from a substring_t
* @s: substring_t to be scanned
* @result: resulting integer on success
*
* Description: Attempts to parse the &substring_t @s as an octal integer. On
* success, sets @result to the integer represented by the string and returns
* 0. Returns -ENOMEM, -EINVAL, or -ERANGE on failure.
*/
int match_octal(substring_t *s, int *result)
{
return match_number(s, result, 8);
}
EXPORT_SYMBOL(match_octal);
/**
* match_hex: - scan a hex representation of an integer from a substring_t
* @s: substring_t to be scanned
* @result: resulting integer on success
*
* Description: Attempts to parse the &substring_t @s as a hexadecimal integer.
* On success, sets @result to the integer represented by the string and
* returns 0. Returns -ENOMEM, -EINVAL, or -ERANGE on failure.
*/
int match_hex(substring_t *s, int *result)
{
return match_number(s, result, 16);
}
EXPORT_SYMBOL(match_hex);
/**
* match_wildcard: - parse if a string matches given wildcard pattern
* @pattern: wildcard pattern
* @str: the string to be parsed
*
* Description: Parse the string @str to check if matches wildcard
* pattern @pattern. The pattern may contain two type wildcardes:
* '*' - matches zero or more characters
* '?' - matches one character
* If it's matched, return true, else return false.
*/
bool match_wildcard(const char *pattern, const char *str)
{
const char *s = str;
const char *p = pattern;
bool star = false;
while (*s) {
switch (*p) {
case '?':
s++;
p++;
break;
case '*':
star = true;
str = s;
if (!*++p)
return true;
pattern = p;
break;
default:
if (*s == *p) {
s++;
p++;
} else {
if (!star)
return false;
str++;
s = str;
p = pattern;
}
break;
}
}
if (*p == '*')
++p;
return !*p;
}
EXPORT_SYMBOL(match_wildcard);
/**
* match_strlcpy: - Copy the characters from a substring_t to a sized buffer
* @dest: where to copy to
* @src: &substring_t to copy
* @size: size of destination buffer
*
* Description: Copy the characters in &substring_t @src to the
* c-style string @dest. Copy no more than @size - 1 characters, plus
* the terminating NUL. Return length of @src.
*/
size_t match_strlcpy(char *dest, const substring_t *src, size_t size)
{
size_t ret = src->to - src->from;
if (size) {
size_t len = ret >= size ? size - 1 : ret;
memcpy(dest, src->from, len);
dest[len] = '\0';
}
return ret;
}
EXPORT_SYMBOL(match_strlcpy);
/**
* match_strdup: - allocate a new string with the contents of a substring_t
* @s: &substring_t to copy
*
* Description: Allocates and returns a string filled with the contents of
* the &substring_t @s. The caller is responsible for freeing the returned
* string with kfree().
*/
char *match_strdup(const substring_t *s)
{
size_t sz = s->to - s->from + 1;
char *p = kmalloc(sz, GFP_KERNEL);
if (p)
match_strlcpy(p, s, sz);
return p;
}
EXPORT_SYMBOL(match_strdup);
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