ext4 uses generic_file_llseek for lseek, and I find this implementation for that in fs/read_write.c:
So really, nothing to it, and the only thing that could be blocking is that mutex...
I think you've saturated the kernel with so many simultaneous system calls to the same inode that they're competing for i_mutex.
I don't think this'd happen if you hadn't opened it with O_DIRECT. Caching is your friend...
Last edited by Corona688; 09-13-2011 at 11:05 AM..
Hi,
I am accepting a string from user. compare this output with the awk output as below...
echo "\n\n\tDay : \c"
read day
awk '{ if($day == $2) { if ($mon == $1) { print "Yes" }}}' syslog.txt
I am getting the follwoing error
awk: Field $() is not correct.
The input line... (5 Replies)
recently my project needs me to lseek a position over 4G size....
i found in linux or unix the parameters are all ulong 32 bits...the limit dooms the movement of a position over 4G
I was told that i should lseek64 to meet my need... but i have no idea where i can get the function neither by "man... (8 Replies)
Hey Guys
I am trying to implement the malloc function for my OS class and I am having a little trouble with it. I would be really grateful if I could get some hints on this problem.
So I am using a doubly-linked list as my data structure and I have to allocate memory for it (duh...). The... (1 Reply)
Hey Guys
Some of my friends have got together and we are trying to write a basic kernel similar to Linux. I am trying to implement the malloc function in C and I am using a doubly linked list as the primary data structure. I need to allocate memory for this link list (duh...) and I don't feel... (2 Replies)
I know there is lseek() function that will allow to write or read from certain position in the file. Is there similar function that will let do same but for array rather then file? (9 Replies)
I tried to use lseek system call to determine the number of bytes in a file. To do so, I used open system call with O_APPEND flag to open a file. As lseek returns the current offset so I called lseek for opened file with offset as zero and whence as SEEK_CUR. So I guess it must return the number of... (3 Replies)
I think both write at the end of the file ......
but is there a sharp difference between those 2 instruction .....
thank you
this is my 3rd question today forgive me :D (1 Reply)
Hi,
We are facing issues while backing up our 1205 GB filesystem on LTO5 Tape. During backup the "backup: The lseek call failed." messages were generated, I want to know why these messages were generating
AIX version is: 6100-08-00-0000
backup: The date of this level 0 backup is Mon Mar 11... (4 Replies)
The following code:
int fd;
if (fd = open("mem", O_RDONLY) == -1)
return 1;
if (lseek(fd, 0, SEEK_SET) == -1) {
char *buf = malloc(512);
buf = strerror(errno);
printf("%s\n", buf);
return 1;
}
always returns with "illegal seek"... (2 Replies)
Discussion started by: Sir_Tomasz
2 Replies
LEARN ABOUT MINIX
lseek
LSEEK(2) System Calls Manual LSEEK(2)NAME
lseek - move read/write pointer
SYNOPSIS
#include <sys/types.h>
#include <unistd.h>
#define SEEK_SET 0 /* offset is absolute */
#define SEEK_CUR 1 /* relative to current position */
#define SEEK_END 2 /* relative to end of file */
off_t lseek(int d, off_t offset, int whence)
DESCRIPTION
The descriptor d refers to a file or device open for reading and/or writing. Lseek sets the file pointer of d as follows:
If whence is SEEK_SET, the pointer is set to offset bytes.
If whence is SEEK_CUR, the pointer is set to its current location plus offset.
If whence is SEEK_END, the pointer is set to the size of the file plus offset.
Upon successful completion, the resulting pointer location as measured in bytes from beginning of the file is returned. Some devices are
incapable of seeking. The value of the pointer associated with such a device is undefined.
NOTES
Seeking far beyond the end of a file, then writing, creates a gap or "hole", which occupies no physical space and reads as zeros.
RETURN VALUE
Upon successful completion, the current file pointer value is returned. Otherwise, a value of -1 is returned and errno is set to indicate
the error.
ERRORS
Lseek will fail and the file pointer will remain unchanged if:
[EBADF] Fildes is not an open file descriptor.
[ESPIPE] Fildes is associated with a pipe or a socket.
[EINVAL] Whence is not a proper value.
SEE ALSO fcntl(2), open(2).
BUGS
This document's use of whence is incorrect English, but maintained for historical reasons.
4th Berkeley Distribution February 24, 1986 LSEEK(2)