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author | Theodore Ts'o <tytso@mit.edu> | 2023-06-08 17:39:35 +0300 |
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committer | Theodore Ts'o <tytso@mit.edu> | 2023-06-27 02:35:12 +0300 |
commit | 4c0cfebdf3c34c9cd2c55844f549fa46b1da3164 (patch) | |
tree | f9e23c6cbd7a7320aefb33a1df85ecb711e56ea1 /fs/ext4/ext4.h | |
parent | ab8627e104696b8c1c6953ad5255def5b0821e06 (diff) | |
download | linux-4c0cfebdf3c34c9cd2c55844f549fa46b1da3164.tar.xz |
ext4: clean up mballoc criteria comments
Line wrap and slightly clarify the comments describing mballoc's
cirtiera.
Define EXT4_MB_NUM_CRS as part of the enum, so that it will
automatically get updated when criteria is added or removed.
Also fix a potential unitialized use of 'cr' variable if
CONFIG_EXT4_DEBUG is enabled.
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Diffstat (limited to 'fs/ext4/ext4.h')
-rw-r--r-- | fs/ext4/ext4.h | 45 |
1 files changed, 25 insertions, 20 deletions
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h index 6a1f013d23f7..45a531446ea2 100644 --- a/fs/ext4/ext4.h +++ b/fs/ext4/ext4.h @@ -128,47 +128,52 @@ enum SHIFT_DIRECTION { }; /* - * Number of criterias defined. For each criteria, mballoc has slightly - * different way of finding the required blocks nad usually, higher the - * criteria the slower the allocation. We start at lower criterias and keep - * falling back to higher ones if we are not able to find any blocks. - */ -#define EXT4_MB_NUM_CRS 5 -/* - * All possible allocation criterias for mballoc. Lower are faster. + * For each criteria, mballoc has slightly different way of finding + * the required blocks nad usually, higher the criteria the slower the + * allocation. We start at lower criterias and keep falling back to + * higher ones if we are not able to find any blocks. Lower (earlier) + * criteria are faster. */ enum criteria { /* - * Used when number of blocks needed is a power of 2. This doesn't - * trigger any disk IO except prefetch and is the fastest criteria. + * Used when number of blocks needed is a power of 2. This + * doesn't trigger any disk IO except prefetch and is the + * fastest criteria. */ CR_POWER2_ALIGNED, /* - * Tries to lookup in-memory data structures to find the most suitable - * group that satisfies goal request. No disk IO except block prefetch. + * Tries to lookup in-memory data structures to find the most + * suitable group that satisfies goal request. No disk IO + * except block prefetch. */ CR_GOAL_LEN_FAST, /* - * Same as CR_GOAL_LEN_FAST but is allowed to reduce the goal length to - * the best available length for faster allocation. + * Same as CR_GOAL_LEN_FAST but is allowed to reduce the goal + * length to the best available length for faster allocation. */ CR_BEST_AVAIL_LEN, /* - * Reads each block group sequentially, performing disk IO if necessary, to - * find find_suitable block group. Tries to allocate goal length but might trim - * the request if nothing is found after enough tries. + * Reads each block group sequentially, performing disk IO if + * necessary, to find find_suitable block group. Tries to + * allocate goal length but might trim the request if nothing + * is found after enough tries. */ CR_GOAL_LEN_SLOW, /* - * Finds the first free set of blocks and allocates those. This is only - * used in rare cases when CR_GOAL_LEN_SLOW also fails to allocate - * anything. + * Finds the first free set of blocks and allocates + * those. This is only used in rare cases when + * CR_GOAL_LEN_SLOW also fails to allocate anything. */ CR_ANY_FREE, + + /* + * Number of criterias defined. + */ + EXT4_MB_NUM_CRS }; /* criteria below which we use fast block scanning and avoid unnecessary IO */ |