get_fatent_value(...) flushes changed FAT entries to disk when fetching the next FAT blocks, in every other aspect it is identical to get_fatent(...).

Provide a stub implementation for flush_dirty_fat_buffer if CONFIG_FAT_WRITE is not set. Calling flush_dirty_fat_buffer during read only operation is fine as it checks if any buffers needs flushing.

Signed-off-by: Stefan Brüns stefan.bruens@rwth-aachen.de Reviewed-by: Benoît Thébaudeau benoit.thebaudeau.dev@gmail.com --- fs/fat/fat.c | 25 ++++++++++-- fs/fat/fat_write.c | 118 +++-------------------------------------------------- 2 files changed, 27 insertions(+), 116 deletions(-)

diff --git a/fs/fat/fat.c b/fs/fat/fat.c index 6319581406..73c3dd7f85 100644 --- a/fs/fat/fat.c +++ b/fs/fat/fat.c @@ -162,6 +162,16 @@ static void get_name(dir_entry *dirent, char *s_name) downcase(s_name); }

+static int flush_dirty_fat_buffer(fsdata *mydata); +#if !defined(CONFIG_FAT_WRITE) +/* Stub for read only operation */ +int flush_dirty_fat_buffer(fsdata *mydata) +{ + (void)(mydata); + return 0; +} +#endif + /* * Get the entry at index 'entry' in a FAT (12/16/32) table. * On failure 0x00 is returned. @@ -173,6 +183,11 @@ static __u32 get_fatent(fsdata *mydata, __u32 entry) __u32 ret = 0x00; __u16 val1, val2;

+ if (CHECK_CLUST(entry, mydata->fatsize)) { + printf("Error: Invalid FAT entry: 0x%08x\n", entry); + return ret; + } + switch (mydata->fatsize) { case 32: bufnum = entry / FAT32BUFSIZE; @@ -192,7 +207,7 @@ static __u32 get_fatent(fsdata *mydata, __u32 entry) return ret; }

- debug("FAT%d: entry: 0x%04x = %d, offset: 0x%04x = %d\n", + debug("FAT%d: entry: 0x%08x = %d, offset: 0x%04x = %d\n", mydata->fatsize, entry, entry, offset, offset);

/* Read a new block of FAT entries into the cache. */ @@ -208,6 +223,10 @@ static __u32 get_fatent(fsdata *mydata, __u32 entry)

startblock += mydata->fat_sect; /* Offset from start of disk */

+ /* Write back the fatbuf to the disk */ + if (flush_dirty_fat_buffer(mydata) < 0) + return -1; + if (disk_read(startblock, getsize, bufptr) < 0) { debug("Error reading FAT blocks\n"); return ret; @@ -254,8 +273,8 @@ static __u32 get_fatent(fsdata *mydata, __u32 entry) } break; } - debug("FAT%d: ret: %08x, offset: %04x\n", - mydata->fatsize, ret, offset); + debug("FAT%d: ret: 0x%08x, entry: 0x%08x, offset: 0x%04x\n", + mydata->fatsize, ret, entry, offset);

return ret; } diff --git a/fs/fat/fat_write.c b/fs/fat/fat_write.c index 0be60ecd99..c05fc7f099 100644 --- a/fs/fat/fat_write.c +++ b/fs/fat/fat_write.c @@ -143,114 +143,6 @@ static int flush_dirty_fat_buffer(fsdata *mydata) }

/* - * Get the entry at index 'entry' in a FAT (12/16/32) table. - * On failure 0x00 is returned. - * When bufnum is changed, write back the previous fatbuf to the disk. - */ -static __u32 get_fatent_value(fsdata *mydata, __u32 entry) -{ - __u32 bufnum; - __u32 off16, offset; - __u32 ret = 0x00; - __u16 val1, val2; - - if (CHECK_CLUST(entry, mydata->fatsize)) { - printf("Error: Invalid FAT entry: 0x%08x\n", entry); - return ret; - } - - switch (mydata->fatsize) { - case 32: - bufnum = entry / FAT32BUFSIZE; - offset = entry - bufnum * FAT32BUFSIZE; - break; - case 16: - bufnum = entry / FAT16BUFSIZE; - offset = entry - bufnum * FAT16BUFSIZE; - break; - case 12: - bufnum = entry / FAT12BUFSIZE; - offset = entry - bufnum * FAT12BUFSIZE; - break; - - default: - /* Unsupported FAT size */ - return ret; - } - - debug("FAT%d: entry: 0x%04x = %d, offset: 0x%04x = %d\n", - mydata->fatsize, entry, entry, offset, offset); - - /* Read a new block of FAT entries into the cache. */ - if (bufnum != mydata->fatbufnum) { - int getsize = FATBUFBLOCKS; - __u8 *bufptr = mydata->fatbuf; - __u32 fatlength = mydata->fatlength; - __u32 startblock = bufnum * FATBUFBLOCKS; - - /* Cap length if fatlength is not a multiple of FATBUFBLOCKS */ - if (startblock + getsize > fatlength) - getsize = fatlength - startblock; - - startblock += mydata->fat_sect; /* Offset from start of disk */ - - /* Write back the fatbuf to the disk */ - if (flush_dirty_fat_buffer(mydata) < 0) - return -1; - - if (disk_read(startblock, getsize, bufptr) < 0) { - debug("Error reading FAT blocks\n"); - return ret; - } - mydata->fatbufnum = bufnum; - } - - /* Get the actual entry from the table */ - switch (mydata->fatsize) { - case 32: - ret = FAT2CPU32(((__u32 *) mydata->fatbuf)[offset]); - break; - case 16: - ret = FAT2CPU16(((__u16 *) mydata->fatbuf)[offset]); - break; - case 12: - off16 = (offset * 3) / 4; - - switch (offset & 0x3) { - case 0: - ret = FAT2CPU16(((__u16 *) mydata->fatbuf)[off16]); - ret &= 0xfff; - break; - case 1: - val1 = FAT2CPU16(((__u16 *)mydata->fatbuf)[off16]); - val1 &= 0xf000; - val2 = FAT2CPU16(((__u16 *)mydata->fatbuf)[off16 + 1]); - val2 &= 0x00ff; - ret = (val2 << 4) | (val1 >> 12); - break; - case 2: - val1 = FAT2CPU16(((__u16 *)mydata->fatbuf)[off16]); - val1 &= 0xff00; - val2 = FAT2CPU16(((__u16 *)mydata->fatbuf)[off16 + 1]); - val2 &= 0x000f; - ret = (val2 << 8) | (val1 >> 8); - break; - case 3: - ret = FAT2CPU16(((__u16 *)mydata->fatbuf)[off16]); - ret = (ret & 0xfff0) >> 4; - break; - default: - break; - } - break; - } - debug("FAT%d: ret: %08x, entry: %08x, offset: %04x\n", - mydata->fatsize, ret, entry, offset); - - return ret; -} - -/* * Set the file name information from 'name' into 'slotptr', */ static int str2slot(dir_slot *slotptr, const char *name, int *idx) @@ -407,7 +299,7 @@ get_long_file_name(fsdata *mydata, int curclust, __u8 *cluster, if ((__u8 *)slotptr >= buflimit) { if (curclust == 0) return -1; - curclust = get_fatent_value(mydata, dir_curclust); + curclust = get_fatent(mydata, dir_curclust); if (CHECK_CLUST(curclust, mydata->fatsize)) { debug("curclust: 0x%x\n", curclust); printf("Invalid FAT entry\n"); @@ -539,7 +431,7 @@ static __u32 determine_fatent(fsdata *mydata, __u32 entry) __u32 next_fat, next_entry = entry + 1;

while (1) { - next_fat = get_fatent_value(mydata, next_entry); + next_fat = get_fatent(mydata, next_entry); if (next_fat == 0) { /* found free entry, link to entry */ set_fatent_value(mydata, entry, next_entry); @@ -625,7 +517,7 @@ static int find_empty_cluster(fsdata *mydata) __u32 fat_val, entry = 3;

while (1) { - fat_val = get_fatent_value(mydata, entry); + fat_val = get_fatent(mydata, entry); if (fat_val == 0) break; entry++; @@ -673,7 +565,7 @@ static int clear_fatent(fsdata *mydata, __u32 entry) __u32 fat_val;

while (1) { - fat_val = get_fatent_value(mydata, entry); + fat_val = get_fatent(mydata, entry); if (fat_val != 0) set_fatent_value(mydata, entry, 0); else @@ -951,7 +843,7 @@ static dir_entry *find_directory_entry(fsdata *mydata, int startsect, return NULL; }

- curclust = get_fatent_value(mydata, dir_curclust); + curclust = get_fatent(mydata, dir_curclust); if (IS_LAST_CLUST(curclust, mydata->fatsize)) { empty_dentptr = dentptr; return NULL;