page_cache_readahead(9)

NAME

page_cache_readahead - generic adaptive readahead

SYNOPSIS

unsigned long page_cache_readahead(struct address_space  *
mapping,  struct  file_ra_state * ra, struct file * filp, pgoff_t
offset, unsigned long req_size);

ARGUMENTS

mapping

address_space which holds the pagecache and I/O vectors

ra

file_ra_state which holds the readahead state

filp

passed on to ->readpage and ->readpages

offset

start offset into mapping, in PAGE_CACHE_SIZE units

req_size

hint: total size of the read which the caller is per

forming in PAGE_CACHE_SIZE units

DESCRIPTION

page_cache_readahead is the main function. If performs the

adaptive readahead window size management and submits the reada

head I/O.

Note that filp is purely used for passing on to the

->readpage[s]()

HANDLER

it may refer to a different file from mapping (so we may

not use filp->f_mapping or filp->f_dentry->d_inode here). Also,

ra may not be equal to &filp->f_ra.

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PAGE_CACHE_READAHEAD(9)