mirror of
https://github.com/eledio-devices/thirdparty-littlefs.git
synced 2025-11-01 00:38:29 +01:00
2936514b5e
The "move problem" has been present in littlefs for a while, but I haven't come across a solution worth implementing for various reasons. The problem is simple: how do we move directory entries across directories atomically? Since multiple directory entries are involved, we can't rely entirely on the atomic block updates. It ends up being a bit of a puzzle. To make the problem more complicated, any directory block update can fail due to wear, and cause the directory block to need to be relocated. This happens rarely, but brings a large number of corner cases. --- The solution in this patch is simple: 1. Mark source as "moving" 2. Copy source to destination 3. Remove source If littlefs ever runs into a "moving" entry, that means a power loss occured during a move. Either the destination entry exists or it doesn't. In this case we just search the entire filesystem for the destination entry. This is expensive, however the chance of a power loss during a move is relatively low.
58 lines
814 B
Makefile
58 lines
814 B
Makefile
TARGET = lfs
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CC = gcc
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AR = ar
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SIZE = size
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SRC += $(wildcard *.c emubd/*.c)
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OBJ := $(SRC:.c=.o)
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DEP := $(SRC:.c=.d)
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ASM := $(SRC:.c=.s)
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TEST := $(patsubst tests/%.sh,%,$(wildcard tests/test_*))
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ifdef DEBUG
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CFLAGS += -O0 -g3
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else
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CFLAGS += -Os
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endif
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ifdef WORD
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CFLAGS += -m$(WORD)
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endif
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CFLAGS += -I.
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CFLAGS += -std=c99 -Wall -pedantic
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all: $(TARGET)
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asm: $(ASM)
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size: $(OBJ)
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$(SIZE) -t $^
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.SUFFIXES:
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test: test_format test_dirs test_files test_seek test_parallel \
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test_alloc test_paths test_orphan test_move test_corrupt
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test_%: tests/test_%.sh
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./$<
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-include $(DEP)
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$(TARGET): $(OBJ)
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$(CC) $(CFLAGS) $^ $(LFLAGS) -o $@
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%.a: $(OBJ)
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$(AR) rcs $@ $^
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%.o: %.c
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$(CC) -c -MMD $(CFLAGS) $< -o $@
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%.s: %.c
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$(CC) -S $(CFLAGS) $< -o $@
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clean:
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rm -f $(TARGET)
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rm -f $(OBJ)
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rm -f $(DEP)
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rm -f $(ASM)
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