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Small improvement in FAT buffering logic on write()

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git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@3957 42af7a65-404d-4744-a932-0658087f49c3
This commit is contained in:
patacongo 2011-09-15 23:06:41 +00:00
parent 6720018ae9
commit 89cd802c03
2 changed files with 17 additions and 14 deletions
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27
fs/fat/fs_fat32.c
View File

@ -708,14 +708,6 @@ static ssize_t fat_write(FAR struct file *filep, const char *buffer,
while (buflen > 0) while (buflen > 0)
{ {
/* Check if there is unwritten data in the file buffer */
ret = fat_ffcacheflush(fs, ff);
if (ret < 0)
{
goto errout_with_semaphore;
}
/* Check if the user has provided a buffer large enough to /* Check if the user has provided a buffer large enough to
* hold one or more complete sectors. * hold one or more complete sectors.
*/ */
@ -737,7 +729,8 @@ static ssize_t fat_write(FAR struct file *filep, const char *buffer,
} }
/* We are not sure of the state of the file buffer so /* We are not sure of the state of the file buffer so
* the safest thing to do is just invalidate it * the safest thing to do is write back any dirty, cached sector
* and invalidate the current cache content.
*/ */
(void)fat_ffcacheinvalidate(fs, ff); (void)fat_ffcacheinvalidate(fs, ff);
@ -770,6 +763,10 @@ static ssize_t fat_write(FAR struct file *filep, const char *buffer,
if (filep->f_pos < ff->ff_size || sectorindex != 0) if (filep->f_pos < ff->ff_size || sectorindex != 0)
{ {
/* Read the current sector into memory (perhaps first flushing
* the old, dirty sector to disk).
*/
ret = fat_ffcacheread(fs, ff, ff->ff_currentsector); ret = fat_ffcacheread(fs, ff, ff->ff_currentsector);
if (ret < 0) if (ret < 0)
{ {
@ -778,9 +775,15 @@ static ssize_t fat_write(FAR struct file *filep, const char *buffer,
} }
else else
{ {
/* But in this rare case, we do have to mark the unused cached /* Flush unwritten data in the sector cache. */
* buffer as the current buffer.
*/ ret = fat_ffcacheflush(fs, ff);
if (ret < 0)
{
goto errout_with_semaphore;
}
/* Now mark the clean cache buffer as the current sector. */
ff->ff_cachesector = ff->ff_currentsector; ff->ff_cachesector = ff->ff_currentsector;
} }

2
include/fcntl.h
View File

@ -75,7 +75,7 @@
#define F_DUPFD 0 /* Duplicate a file descriptor */ #define F_DUPFD 0 /* Duplicate a file descriptor */
#define F_GETFD 1 /* Read the file descriptor flags */ #define F_GETFD 1 /* Read the file descriptor flags */
#define F_GETFL 2 /* Read the file status flags */ #define F_GETFL 2 /* Read the file status flags */
#define F_GETLEASE 3 /* Indicas what type of lease is held on fd (linux) */ #define F_GETLEASE 3 /* Indicates what type of lease is held on fd (linux) */
#define F_GETLK 4 /* Check if we could place a lock */ #define F_GETLK 4 /* Check if we could place a lock */
#define F_GETOWN 5 /* Get the pid receiving SIGIO and SIGURG signals for fd */ #define F_GETOWN 5 /* Get the pid receiving SIGIO and SIGURG signals for fd */
#define F_GETSIG 6 /* Get the signal sent */ #define F_GETSIG 6 /* Get the signal sent */