diff options
| -rw-r--r-- | fs/ocfs2/buffer_head_io.c | 95 | ||||
| -rw-r--r-- | fs/ocfs2/buffer_head_io.h | 2 | ||||
| -rw-r--r-- | fs/ocfs2/dir.c | 28 | ||||
| -rw-r--r-- | fs/ocfs2/inode.c | 4 | ||||
| -rw-r--r-- | fs/ocfs2/namei.c | 10 | ||||
| -rw-r--r-- | fs/ocfs2/uptodate.c | 21 | ||||
| -rw-r--r-- | fs/ocfs2/uptodate.h | 2 |
7 files changed, 115 insertions, 47 deletions
diff --git a/fs/ocfs2/buffer_head_io.c b/fs/ocfs2/buffer_head_io.c index 9a24adf..c903741 100644 --- a/fs/ocfs2/buffer_head_io.c +++ b/fs/ocfs2/buffer_head_io.c @@ -100,6 +100,9 @@ int ocfs2_read_blocks(struct ocfs2_super *osb, u64 block, int nr, mlog_entry("(block=(%llu), nr=(%d), flags=%d, inode=%p)\n", (unsigned long long)block, nr, flags, inode); + BUG_ON((flags & OCFS2_BH_READAHEAD) && + (!inode || !(flags & OCFS2_BH_CACHED))); + if (osb == NULL || osb->sb == NULL || bhs == NULL) { status = -EINVAL; mlog_errno(status); @@ -140,6 +143,30 @@ int ocfs2_read_blocks(struct ocfs2_super *osb, u64 block, int nr, bh = bhs[i]; ignore_cache = 0; + /* There are three read-ahead cases here which we need to + * be concerned with. All three assume a buffer has + * previously been submitted with OCFS2_BH_READAHEAD + * and it hasn't yet completed I/O. + * + * 1) The current request is sync to disk. This rarely + * happens these days, and never when performance + * matters - the code can just wait on the buffer + * lock and re-submit. + * + * 2) The current request is cached, but not + * readahead. ocfs2_buffer_uptodate() will return + * false anyway, so we'll wind up waiting on the + * buffer lock to do I/O. We re-check the request + * with after getting the lock to avoid a re-submit. + * + * 3) The current request is readahead (and so must + * also be a caching one). We short circuit if the + * buffer is locked (under I/O) and if it's in the + * uptodate cache. The re-check from #2 catches the + * case that the previous read-ahead completes just + * before our is-it-in-flight check. + */ + if (flags & OCFS2_BH_CACHED && !ocfs2_buffer_uptodate(inode, bh)) { mlog(ML_UPTODATE, @@ -169,6 +196,14 @@ int ocfs2_read_blocks(struct ocfs2_super *osb, u64 block, int nr, continue; } + /* A read-ahead request was made - if the + * buffer is already under read-ahead from a + * previously submitted request than we are + * done here. */ + if ((flags & OCFS2_BH_READAHEAD) + && ocfs2_buffer_read_ahead(inode, bh)) + continue; + lock_buffer(bh); if (buffer_jbd(bh)) { #ifdef CATCH_BH_JBD_RACES @@ -181,13 +216,22 @@ int ocfs2_read_blocks(struct ocfs2_super *osb, u64 block, int nr, continue; #endif } + + /* Re-check ocfs2_buffer_uptodate() as a + * previously read-ahead buffer may have + * completed I/O while we were waiting for the + * buffer lock. */ + if ((flags & OCFS2_BH_CACHED) + && !(flags & OCFS2_BH_READAHEAD) + && ocfs2_buffer_uptodate(inode, bh)) { + unlock_buffer(bh); + continue; + } + clear_buffer_uptodate(bh); get_bh(bh); /* for end_buffer_read_sync() */ bh->b_end_io = end_buffer_read_sync; - if (flags & OCFS2_BH_READAHEAD) - submit_bh(READA, bh); - else - submit_bh(READ, bh); + submit_bh(READ, bh); continue; } } @@ -197,34 +241,39 @@ int ocfs2_read_blocks(struct ocfs2_super *osb, u64 block, int nr, for (i = (nr - 1); i >= 0; i--) { bh = bhs[i]; - /* We know this can't have changed as we hold the - * inode sem. Avoid doing any work on the bh if the - * journal has it. */ - if (!buffer_jbd(bh)) - wait_on_buffer(bh); - - if (!buffer_uptodate(bh)) { - /* Status won't be cleared from here on out, - * so we can safely record this and loop back - * to cleanup the other buffers. Don't need to - * remove the clustered uptodate information - * for this bh as it's not marked locally - * uptodate. */ - status = -EIO; - brelse(bh); - bhs[i] = NULL; - continue; + if (!(flags & OCFS2_BH_READAHEAD)) { + /* We know this can't have changed as we hold the + * inode sem. Avoid doing any work on the bh if the + * journal has it. */ + if (!buffer_jbd(bh)) + wait_on_buffer(bh); + + if (!buffer_uptodate(bh)) { + /* Status won't be cleared from here on out, + * so we can safely record this and loop back + * to cleanup the other buffers. Don't need to + * remove the clustered uptodate information + * for this bh as it's not marked locally + * uptodate. */ + status = -EIO; + brelse(bh); + bhs[i] = NULL; + continue; + } } + /* Always set the buffer in the cache, even if it was + * a forced read, or read-ahead which hasn't yet + * completed. */ if (inode) ocfs2_set_buffer_uptodate(inode, bh); } if (inode) mutex_unlock(&OCFS2_I(inode)->ip_io_mutex); - mlog(ML_BH_IO, "block=(%llu), nr=(%d), cached=%s\n", + mlog(ML_BH_IO, "block=(%llu), nr=(%d), cached=%s, flags=0x%x\n", (unsigned long long)block, nr, - (!(flags & OCFS2_BH_CACHED) || ignore_cache) ? "no" : "yes"); + (!(flags & OCFS2_BH_CACHED) || ignore_cache) ? "no" : "yes", flags); bail: diff --git a/fs/ocfs2/buffer_head_io.h b/fs/ocfs2/buffer_head_io.h index 6ecb909..6cc2093 100644 --- a/fs/ocfs2/buffer_head_io.h +++ b/fs/ocfs2/buffer_head_io.h @@ -49,7 +49,7 @@ int ocfs2_read_blocks(struct ocfs2_super *osb, #define OCFS2_BH_CACHED 1 -#define OCFS2_BH_READAHEAD 8 /* use this to pass READA down to submit_bh */ +#define OCFS2_BH_READAHEAD 8 static inline int ocfs2_read_block(struct ocfs2_super * osb, u64 off, struct buffer_head **bh, int flags, diff --git a/fs/ocfs2/dir.c b/fs/ocfs2/dir.c index 3d494d1..04e0191 100644 --- a/fs/ocfs2/dir.c +++ b/fs/ocfs2/dir.c @@ -74,14 +74,14 @@ static int ocfs2_extend_dir(struct ocfs2_super *osb, int ocfs2_readdir(struct file * filp, void * dirent, filldir_t filldir) { int error = 0; - unsigned long offset, blk; - int i, num, stored; + unsigned long offset, blk, last_ra_blk = 0; + int i, stored; struct buffer_head * bh, * tmp; struct ocfs2_dir_entry * de; int err; struct inode *inode = filp->f_dentry->d_inode; struct super_block * sb = inode->i_sb; - int have_disk_lock = 0; + unsigned int ra_sectors = 16; mlog_entry("dirino=%llu\n", (unsigned long long)OCFS2_I(inode)->ip_blkno); @@ -95,9 +95,8 @@ int ocfs2_readdir(struct file * filp, void * dirent, filldir_t filldir) mlog_errno(error); /* we haven't got any yet, so propagate the error. */ stored = error; - goto bail; + goto bail_nolock; } - have_disk_lock = 1; offset = filp->f_pos & (sb->s_blocksize - 1); @@ -113,16 +112,21 @@ int ocfs2_readdir(struct file * filp, void * dirent, filldir_t filldir) continue; } - /* - * Do the readahead (8k) - */ - if (!offset) { - for (i = 16 >> (sb->s_blocksize_bits - 9), num = 0; + /* The idea here is to begin with 8k read-ahead and to stay + * 4k ahead of our current position. + * + * TODO: Use the pagecache for this. We just need to + * make sure it's cluster-safe... */ + if (!last_ra_blk + || (((last_ra_blk - blk) << 9) <= (ra_sectors / 2))) { + for (i = ra_sectors >> (sb->s_blocksize_bits - 9); i > 0; i--) { tmp = ocfs2_bread(inode, ++blk, &err, 1); if (tmp) brelse(tmp); } + last_ra_blk = blk; + ra_sectors = 8; } revalidate: @@ -194,9 +198,9 @@ revalidate: stored = 0; bail: - if (have_disk_lock) - ocfs2_meta_unlock(inode, 0); + ocfs2_meta_unlock(inode, 0); +bail_nolock: mlog_exit(stored); return stored; diff --git a/fs/ocfs2/inode.c b/fs/ocfs2/inode.c index 3f496c4..7bcf691 100644 --- a/fs/ocfs2/inode.c +++ b/fs/ocfs2/inode.c @@ -1050,12 +1050,8 @@ struct buffer_head *ocfs2_bread(struct inode *inode, u64 p_blkno; int readflags = OCFS2_BH_CACHED; -#if 0 - /* only turn this on if we know we can deal with read_block - * returning nothing */ if (reada) readflags |= OCFS2_BH_READAHEAD; -#endif if (((u64)block << inode->i_sb->s_blocksize_bits) >= i_size_read(inode)) { diff --git a/fs/ocfs2/namei.c b/fs/ocfs2/namei.c index 2412647..0d3e939 100644 --- a/fs/ocfs2/namei.c +++ b/fs/ocfs2/namei.c @@ -56,6 +56,7 @@ #include "journal.h" #include "namei.h" #include "suballoc.h" +#include "super.h" #include "symlink.h" #include "sysfile.h" #include "uptodate.h" @@ -1962,13 +1963,8 @@ restart: } num++; - /* XXX: questionable readahead stuff here */ bh = ocfs2_bread(dir, b++, &err, 1); bh_use[ra_max] = bh; -#if 0 // ??? - if (bh) - ll_rw_block(READ, 1, &bh); -#endif } } if ((bh = bh_use[ra_ptr++]) == NULL) @@ -1976,6 +1972,10 @@ restart: wait_on_buffer(bh); if (!buffer_uptodate(bh)) { /* read error, skip block & hope for the best */ + ocfs2_error(dir->i_sb, "reading directory %llu, " + "offset %lu\n", + (unsigned long long)OCFS2_I(dir)->ip_blkno, + block); brelse(bh); goto next; } diff --git a/fs/ocfs2/uptodate.c b/fs/ocfs2/uptodate.c index b8a00a7..9707ed7 100644 --- a/fs/ocfs2/uptodate.c +++ b/fs/ocfs2/uptodate.c @@ -206,7 +206,10 @@ static int ocfs2_buffer_cached(struct ocfs2_inode_info *oi, } /* Warning: even if it returns true, this does *not* guarantee that - * the block is stored in our inode metadata cache. */ + * the block is stored in our inode metadata cache. + * + * This can be called under lock_buffer() + */ int ocfs2_buffer_uptodate(struct inode *inode, struct buffer_head *bh) { @@ -226,6 +229,16 @@ int ocfs2_buffer_uptodate(struct inode *inode, return ocfs2_buffer_cached(OCFS2_I(inode), bh); } +/* + * Determine whether a buffer is currently out on a read-ahead request. + * ip_io_sem should be held to serialize submitters with the logic here. + */ +int ocfs2_buffer_read_ahead(struct inode *inode, + struct buffer_head *bh) +{ + return buffer_locked(bh) && ocfs2_buffer_cached(OCFS2_I(inode), bh); +} + /* Requires ip_lock */ static void ocfs2_append_cache_array(struct ocfs2_caching_info *ci, sector_t block) @@ -403,7 +416,11 @@ out_free: * * Note that this function may actually fail to insert the block if * memory cannot be allocated. This is not fatal however (but may - * result in a performance penalty) */ + * result in a performance penalty) + * + * Readahead buffers can be passed in here before the I/O request is + * completed. + */ void ocfs2_set_buffer_uptodate(struct inode *inode, struct buffer_head *bh) { diff --git a/fs/ocfs2/uptodate.h b/fs/ocfs2/uptodate.h index 01cd32d..2e73206 100644 --- a/fs/ocfs2/uptodate.h +++ b/fs/ocfs2/uptodate.h @@ -40,5 +40,7 @@ void ocfs2_set_new_buffer_uptodate(struct inode *inode, struct buffer_head *bh); void ocfs2_remove_from_cache(struct inode *inode, struct buffer_head *bh); +int ocfs2_buffer_read_ahead(struct inode *inode, + struct buffer_head *bh); #endif /* OCFS2_UPTODATE_H */ |
